If you want to know the details of how SIP trunking works, then I will explain here everything you need to know and the process too.

What Is SIP Trunking?

A SIP trunk is an essential system of virtual bundles of voice channels carried over IP by using SIP. It works for the setup, management, and tear-down of phone calls. Otherwise, traditional copper phone lines aren’t like these. It’s costly, a maintenance hassle, and has weather-related issues. That’s why people are moving to the SIP or internet-based communication system. 

Key advantages:

• Scalability: You can add or remove channels on demand.
  
• Cost Efficiency: pay per channel or minute, no physical lines.
  
• Feature-Rich: Leverage advanced call routing, disaster recovery, and codecs.

Core Components & Roles

IP-PBX or Hosted PBX
Your on-prem or cloud-hosted telephony platforms, such as Free PBX, Cisco CUCM, 3CX, or our Cloud PBX that manages extension, call routing, and voicemail, etc.

Session Border Controller (SBC)
Acts as a security and interoperability gatekeeper that hides your internal IP scheme, enforces encryption, and applies SIP normalization

Internet Telephony Service Provider (ITSP)
The Voice providers that terminate calls to the PSTN or other SIP networks and allocate you a pool of DIDs with the voice channels.

Media Path (RTP/RTCP)
Carries actual voice packets, typically RTP with RTCP for quality control.  It may traverse a separate media proxy or go peer-to-peer via NAT traversable techniques.

Signaling Path, SIP Messages: INVITE, 180 Ringing, 200 OK, ACK, BYE, etc., traveling over UDP/TCP/TLS.

How SIP and VoIP Work Together

Well, VoIP is the technology that businesses use to communicate. As well, SIP is the methods or protocol that execute its technology for terminating voice. 

If I want to be more clear with the real thought, I think VoIP is a car and SIP is the engine of this system. 

Real-World Example

MondoTalk’s Cloud PBX:

Using VoIP, you can make calls to the customer using broadband. SIP trunks to connect clients’ PBX systems to MondoTalk’s core telecom network. It offers IVR, Call transfer, CRM, MS team integration, Voice to email, mobile apps, and failover routing. 

Common Combination Setup:

Component	Technology
Softphone App	VoIP (with SIP)
IP Desk Phone	SIP-enabled
PBX System	SIP-based (Cloud or On-Premise)
Call Routing & Trunking	SIP Trunks
Internet Connection	Underlying VoIP Carrier

 How SIP Trunking Works The Process

Let’s break down step by step what happens when you make a VoIP Call through SIP trunking.

1. Call Initiation (SIP Signaling Begins)

The moment you dial a number, your IP PBX generates a SIP INVITE message.

This INVITE packet includes:

• Caller ID
  
• Callee’s number
  
• Codec preferences
  
• Authentication details
  

Then the message reached the SIP provider such as MondoTalk, Ufonii, or Twilio.

2. SIP Trunk Authentication and Routing

The provider receives your INVITE and authenticates it for use with username/password. This authentication will be IP-based. I mean whitelisted IPs. Once authenticated, the SIP server then checks the destination numbers and chooses the best route.

3. Media Negotiation (RTP Stream Setup)

• SIP only sets up the session, and voice is sent via RTP( Real Time Transport Protocol).
  
• Once the destination accepts the call, like a SIP 200 OK, both parties start sending voice data as audio packets.
  
• RTP ports that are typically 10000-20000 open up dynamically, and NAT traversal or STUN/TURN are used if needed.
  

4. Call Connection and Ongoing Session

• During the call:
  
  • SIP monitors session health via OPTIONS and SIP keep-alives.
    
  • Media streams flow back and forth using RTP.
    
• Features such as DTMF tones, call recording, or transferring are also handled via in-band RTP or SIP info/notify messages.
  

 5. Call Termination

• Either party hangs up: sends a SIP BYE message.
  
• Provider replies with 200 OK, confirming the call is terminated.
  
• Call Detail Records (CDRs) are generated for billing and logs.
  

Layer	Protocols / Processes
Signaling	SIP (RFC 3261), with SIP Methods (INVITE, BYE, REGISTER, OPTIONS, etc.)
Media	RTP (RFC 3550), optionally SRTP for encryption
NAT Traversal	STUN, TURN, ICE (for peer-to-peer media)
Security	TLS for SIP, SRTP for media, ACLs on SBC
Codec Negotiation	SDP offer/answer; common codecs: G.711, G.722, G.729
Numbering Plan	E.164 formatting, digit manipulation rules

Real-World Example

Example: Retail Call Center with Cloud PBX

Company: Local Australian electronics retailer
Setup:

• 1 cloud PBX (3CX)
  
• SIP trunk
  
• 30 concurrent calls
  

How it works daily:

1. Customer calls 1300 number: hits Ufonii SIP servers.
   
2. Ufonii routes call their 3CX IP PBX.
   
3. IVR picks up routes to departments.
   
4. Agents use softphones (Zoiper/Bria) or IP phones.
   
5. Voice quality is monitored in real-time via MOS scoring.
   
6. CDRs sync into Zoho CRM for call reports.
   

Personal Experience Insight:

We once had intermittent audio drops on rainy days. It turned out to be a poor-quality router at the retail site doing SIP ALG rewrites. We replaced it with a proper SIP-friendly route,r and the issue disappeared.

Example: Legal Firm

Helped a mid-size legal firm with 75 extensions replace their aging PRI circuits with a pair of redundant SIP trunks. They’d been paying for 23 channels on two ISDN PRIs. 

Preparation Steps:

1. Bandwidth Assessment

Run a year’s worth of call logs and peak concurrent calls: 18. It allocates 100 kbps per G.711 call, 1.8 Mbps plus overhead, and 3 Mbps reserved.

2. SBC Deployment
   

Installing an on-premises SBC and configuring TLS on port 5061. It defined IP ACLs so that only the ITSP’s signaling IPs could connect.

3. PBX Configuration
   You can create two outbound trunks on the PBX:
   
   • SIP-Primary (UDP/5060, priority 1)
     
   • SIP-Backup (TCP/TLS/5061, priority 2): Set up inbound routes mapping each DID to a departmental ring group.
     
4. Test Calls & Failover

Then you can verify calls over SIP primary to PSTN. The system simulated failure by shutting off the primary, and calls seamlessly failed over to the backup.

5. Monitoring & QoS

Then configure SNMP polling on the SBC for call count, SIP errors, and set diffServ DSCP EF for RTP and CS3 for SIP to prioritize voice.

SIP Trunking: Common Technical Components

Component	Role in SIP Trunking
SIP Proxy	Handles SIP message routing & signaling
Registrar Server	Authenticates users/IPs
RTP Engine	Handles actual audio/video streaming
SBC (Session Border Controller)	Security, NAT traversal, protocol normalization
Media Gateway	Converts SIP to TDM for PSTN interconnects

Behind-the-Scenes Security

• SIP over TLS: Encrypts signaling messages (prevents spoofing)
  
• SRTP:  Encrypts RTP audio (prevents call tapping)
  
• SBCs: Firewall + protocol guard
  
• Call Limits & IP ACLs:  Prevent fraud
  

Personal Expertise: Lessons from the Field

• Never underestimate the power of good call logs.
  If there is a SIP 503 or 408 error, then reading the SIP invite header, RTP latency, and timing in Wireshark has solved countries
  
• Carrier Hops Matter:
  A poor SIP provider might route your call through 4-5 unnecessary hops, creating jitter, which reliable providers like Ufonii route more directly.
  
• Don’t DIY NAT Traversal:
  Always use proper NAT rules and test with external SIP test tools like sipvicious or VoIPmonitor.
  
• Real Call Center Experience:  A major partner once migrated from ISDN to SIP trunking. Then the experience with SIP trunk, such as post migration, and they were able to slash their monthly bill by 40%, and they were able to add auto call routing and enable CRM integration.
  

Benefits Recap

SIP Trunking Advantage	Explanation
Scalability	Add/remove call capacity instantly
Cost Efficiency	No per-line charges like PSTN
Flexibility	Can be used across geographies with one trunk
Integration	Easily integrates with CRMs, APIs
Advanced Features	Call forwarding, recording, transcription, so on etc.

Testing Tools & Protocols

• Wireshark – Packet capture for SIP, RTP.
  
• sngrep – CLI SIP session viewer
  
• VoIP monitor – Call quality analytics
  
• SIP – SIP stress testing tool
  
• 3CX / Asterisk / FreePBX – Real PBX platforms to test with
  

 Final Thoughts

SIP trunking is the backbone of the modern communication system.. Behind this scene, there are lots of dependencies such as a symphony of protocols, routing, codecs, and media negotiation. The beauty is in how many moving parts come together to make a simple” hello ”work. I mean it started from INVITE packets to RTP streams and from NAT traversal to carrier selection.

When it works well, it feels like magic. 

FAQs

What happens when I make a SIP trunk call?

When you make a SIP trunk call, your phone system sends a SIP invitation packet to your VoIP provider. This includes the dialed number, caller ID, and preferred audio settings. The provider routes the call to the destination, and once answered, media flows directly via RTP. SIP keeps the session alive, monitors connection health, and handles call termination when either party hangs up.

How does SIP trunking connect to the public telephone network (PSTN)?

That’s a great question. Generally, SIP trunking connects to the PSTN via your VoIP provider, which acts as a gateway. Once your call reaches the provider’s SIP servers, it is routed through their carrier network and translated into a traditional phone call that can be handled by legacy telephone systems. It enables the voip to make landline or VoIP to mobile calls seamlessly. 

Is SIP trunking secure?

Yes, SIP trunks are secure for businesses. But it requires a proper setup before using. SIP trunking generally uses protocols like SIP over TLS and SRTP to encrypt signaling and media streams. Session border controllers also help protect against fraud, unauthorized access, and DDoS attacks. The firewalls should be configured to avoid exposing SIP ports unnecessarily.

Why is RTP used in SIP trunking, and what is it?

RTP( Real Time Transport Protocol is used to carry the actual voice data once a call is established. While SIP handles the signaling, RTP transmits the audio packets in real time. The separation ensures flexibility and allows for better quality control and troubleshooting.

What are the most common issues with SIP trunking?

The most common SIP trunking issues include:

• One-way or no audio. It usually happens due to NAT/firewall misconfiguration.
  
• Call drops (caused by SIP timeouts or router issues)
  
• Codec mismatches
  
• SIP ALG interference on routers

How many calls can a SIP trunk handle?

A single SIP trunk can support multiple concurrent calls, it’s depending on your provider and bandwidth. Each simultaneous call typically requires around 100 Kbps with the G.711 codec, so your internet connection and trunk plan determine the actual capacity. Businesses can scale easily by increasing call channels.

What equipment is needed for SIP trunking?

To use SIP trunking, you typically need

• IP PBX such as 3CX, FreePBX, and Cloud-based PBX
• A router and a stable internet connection
• SIP trunk provider credentials
• VoIP phones, softphones, or analog phones with ATA adapters
  

 

 

VOIP is a voice-over-internet communication system.  It helps businesses communicate with their business partners or employees in the office or remotely. It’s an internet-based communication system connecting remote offices for better communication. 

 

• Why is VOIP Popular?
  • Cost-effective for businesses.
  • Scalable for organizations growth.
  • Flexibility in remote work setup.
  • Easy to integrate any system like CRM, Chatbot, Microsoft team, etc.

VOIP Security Threats

• Eavesdropping: Intercepting voice traffic to listen to private conversations. 
• Phishing and Vishing: Social engineering attacks targeting VOIP users to steal credentials or gain unauthorized access. 
• Denial-of-Service (DoS) Attacks: Overloading the VOIP system to cause disruptions.
• VoIP Fraud: Exploit the system and make a firewall to unauthorize fraudulent calls. 
• Call Hijacking: Taking control of an ongoing VOIP call to redirect traffic or listen in.

 

Why is VoIP security system important?

Since VOIP transmits voice data over the internet using SIP and also the real-time transport Protocol. 

Here are some value option why are VOIP security important:

• Hackers interception calls
• Unauthorized call rerouting and fraud
• Overloading the VOIP system
• Fake caller IDs to deceive users

 

Key Security Concepts for VOIP

 

Authentication

• Importance of Strong Authentication:
  • Use complex passwords for user and administrator accounts.
  • It enables the multi-factor authentication that makes your system strong and prevents unauthorized access to your interface. 
  • By limiting VOIP access, you can secure your settings. This should be done from the user’s site or administration. It can also ensure the security of SIP accounts that are not easy to access and avoid using default settings. 

Encryption

• SIP over TLS can secure signaling traffic to prevent interception during the call setup. VPNs are the private levels of a network used for private communication. They ensure the communication of remote users. 

Firewalls and Access Controls

• A firewall is one kind of protection system that protects fraud access to your communication network. VLANs which are special improve the security of the site. Most importantly ensure that your SIP is perfectly configured with ALG. Then you can eradicate the NAT issues by measuring your security system,

Intrusion Detection and Prevention

• IDS/IPS for VOIP: Set up an intrusion detection or prevention system to monitor the unusual or malicious traffic to the system. Because it’s an indication that I’ll refer to an attack on the system. It’s an outstanding system that always monitors VOIP system traffic such as a spike in call volume or unusual IP addresses. 

 

 

 

 

 

 

 

 

 

Common VOIP Security Risks and How to Mitigate Them

1. Unauthorized Access and Account Hijacking

• Risk: Attackers may gain unauthorized access to the VOIP system, Steal credentials, or take control of the system from the backside. It’s very hearted when you can see the calls are controlled by others and affect your overall security system.
• Mitigation:
  • Use strong, unique passwords for all accounts.
  • Implement multi-factor authentication (MFA).
  • Regularly audit account activity and access logs.
  • Disable unused accounts.
  • Update password every 60 to 90 days.

2. Man-in-the-Middle (MITM) Attacks

• Risk: These types of attackers could intercept the communication endpoints, potentially listening to the calls. 
• Mitigation:
  • Use SIP over TLS for encrypting signaling.
  • Use SRTP to ensure a secure media stream.
  • Encrypt data transmitted between VOIP endpoints.

3. Denial of Service (DoS) and Distributed Denial of Service (DDoS) Attacks

• Risk: Attackers overload the VoIP server with traffic that causes service outages. 
• Mitigation:
  • Deploy firewalls with rate-limiting capabilities to block traffic surges.
  • Use specialized DDoS protection services.
  • Keep VOIP software up to date with the security patches. 

4. VoIP Fraud and Toll Fraud

• Risk: Malicious users would exploit the VOIP system that works in unauthorized long-distance or international calls which leads to financial loss.
• Mitigation:
  • Set up call limits and alerts for high-cost calls.
  • Implement the call detail records and monitor the unusual call patterns 
  • Required, strong authentication for external access like SIP trunking provider. 

5. Phishing and Vishing

• Risk: Social engineering attacks trick users into providing sensitive information over VOIP.
• Mitigation:
  • Train employees to recognize phishing attempts.
  • Always verify calls from unknown numbers before sharing sensitive information.
  • Block calls from suspicious or unauthorized numbers.

Best Practices for VOIP Security

Securing VOIP Devices

• Strong Passwords for Devices: You would ensure a strong password in the used devices like IP phones, Softphones, and other VOIP devices. 
• Firmware Updates: Regularly update the VOIP devices and software to address known Vulnerabilities. 
• Disable Unnecessary Features: instant disable unnecessary VoIP features that manage the remote management and unusual protocols. 

Securing VOIP Networks

• Network Segmentation: Create Separate VLANDs for VOIP traffic to isolate it from other data traffic and prevent cross-contamination. 
• QoS (Quality of Service): Ensure the VoIP packets are prioritized in the network to prevent latency, Jitter, or packet loss. 
• Firewalls: Use firewalls to restrict the external access to the VOIP system and block them

User Awareness and Training

• Phishing and Social Engineering Awareness: Teach employees how to recognize phishing attempts and avoid falling victim to scams. 
• Regular Security Training: Hold on the periodic security and make awareness sessions. It makes sense to the users and informs them about the latest VoIP threats and security best practices. 

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Responding to VOIP Security Incidents

Incident Response Plan

• Identify the Threat: Quickly identify the type of attack like DDoS, eavesdropping, and fraud. 
• Contain the Threat: Isolate the affected system that has blocked IP addresses and disable compromised accounts.
• Eradicate the Threat: Remove malware or other malicious software from the VOIP system.
• Recover the System: Restore the service and ensure a system that’s secure before bringing it back online. 

Work with a Trusted VoIP Provider

The important matter here is that, as a VOIP user or service provider, you should think about the security system. You should also have great experience with VoIP and thread handling. Companies want to contract with a service that can give 100% security to their communication systems. They are also definitely looking for a company that can provide a 24/7 support system. 

However, MondoTalk is different. It’s a business-grade communication solution that already helps many businesses solve their business-grade communication problems. With a glorious 20 years of working experience in the VoIP industry, MondoTalk has handled many threads and has been quite successful. People can trust and feel reliable with MondoTalk. 

If you are looking for a telecom company that can provide you with VoIP solutions, then MondoTalk would be best. 

Top VOIP Statistics

This is the percentage of wireless-only adults and children living in houses with only wireless telephones. (By age United States (Jan-Jun, 2022)

 

 

 

 

 

 

 

 

 

 

Source: National Center for Health Statistics

 

 

• 70% of American adults and 83% of children lived in a household without a landline at the end of 2022
• By 2032, the VOIP service market is expected to reach $108.5 billion
• The global UC market is expected to register a CAGR of 17.4% from 2023 to 2030.
• The cloud-based contact center infrastructure market is expected to grow by 26% from 2024 to 2029.
• 82% of businesses reported cost savings when they moved to the cloud
• 85% of organizations will embrace a cloud-first principle by 2025
• 94% of businesses saw an improvement in security after switching to the cloud
• 38% of companies have staff that work from home
• More than 4.7 million people work remotely at least half the time in the United States.
• Vop can help small business to reduce the startup costs by up to 90%
• The price of VOIP system may go up by 3% over the next five years
• 60% of customers prefer to contact businesses by phone
• 76% of businesses offer support outside of traditional business hours
• 76% of companies offer support outside of conventional business
• SIP accounted for over 51% of the security event activity analyzed in 2016
• Nearly 1 in every 6 adults in the US falls victim to scam calls.
• 60% of smartphone users have called a business directly from a Google search
• 59% of employees use a desk phone every day
• 76% of calls go unanswered if they’re from unidentified or unfamiliar phone numbers
• 76% of calls go unanswered if they are from unidentified phone numbers.
• 28% of cyberattacks are aimed at small businesses.

 

Global VOIP Service Market Assessment

Historical Size of the global VoIP market size US $120.7 billion by 2024. It raised an estimated size in 2024 which is US $132.2 billion. Now this market is projected to size about US $349.1 billion by 2034. 

 

Steps of VOIP Security System For Small Business:

 

The VOIP Password Policy should be strong because it’s the best option for VOIP systems to safeguard communication systems. It protects against unauthorized access and cyber threads that seamlessly make sense for your communication. 

 

Is it true? 

 

Yes, I Hope So. I will explain everything we should look after for better performance at a time. 

However, As a primary safeguard of your communication system, a Password policy is best!

At this step, I will explain some very important steps that make sense to keep safe of your communication;

Minimum Password Length: In the VOIP communication system, you should keep a password length of at least 12-16 characters for your administrative, User, and system-level account. 

Longer passwords are indeed more resistant to brute-force attacks. 

Password should include a mix of uppercase and lowercase letters numbers and special characters. Try to avoid common words that people usually accumulate themselves. For example, Password123 or admin 2025. 

Efforts to enable two-factor locker that hit the cyber security system. A multi-factor authentication lock is important when you are going to a VOIP System on your own. Especially for administration or remote access. 

It’s like a verification process. You can be verified by phone number, biometric, or security token. 

You can change your password every 60 to 90 days later. Prevent the reuse of old passwords for specific numbers here and refresh it. 

 

Lockout Mechanisms

• Set a limit on the number of failed login attempts (e.g., 5 attempts) before locking the account or requiring manual intervention to unlock.
• Implement temporary lockout periods (e.g., 15-30 minutes) to mitigate brute-force attacks.

Encrypt Password Storage

• Ensure that passwords are encrypted both at rest and in transit using industry-standard encryption algorithms (e.g., AES-256).
• Avoid storing passwords in plain text to protect against data breaches.

Avoid Default and Weak Passwords

• Remove or change default system passwords for VOIP equipment (e.g., routers, PBX systems, softphones).
• Ensure that any hardware or software devices that come with default passwords are secured upon installation.

User Training and Awareness

• Educate users properly about the importance of strong passwords and best practices. Aware them to save the password system and not share it with anyone. Also, you shouldn’t use the same passwords for the different platforms. 
• Encourage the use of a password manager to store and generate strong passwords. 

Audit and Monitor Account Access

• Regularly audit the accounts. Check and access logs to protect against unusual or unauthorized attempts.
• Monitor the VOIP system for suspicious activities such as IP address or unauthorized configuration. 

Limit Account Privileges

• Implement the principle of least privilege (PoLP) by granting users the minimum level of access necessary to perform their tasks. Implement the principle of Privilege or PoLP by granting users the minimum level of access necessary to perform their tasks. 
• Regularly review and adjust user permissions to ensure they are appropriate.

Use Secure Communication Channels

• Ensure the VoIP traffic encrypted
• Avoid transmitting sensitive information, such as passwords..

Backup and Recovery

• Implement secure backup practices for VOIP configurations and user credentials, ensuring they are protected from unauthorized access.
• Have a process in place to quickly reset or recover lost or compromised passwords without exposing the system to security risks.

Compliance with Standards

• Align password policies with industry standards and regulatory requirements, such as NIST (National Institute of Standards and Technology) guidelines, GDPR, or PCI-DSS, where applicable.

Enable Encryption

Encrypt your VoIP calls to prevent unauthorized interception. Secure the real-time transport protocol and Transport Layer Security. They are commonly used for encrypting voice data and signaling traffic. Check out your VoIP data and ensure your encryption is enabled. 

Encrypted communication reduces the risk of data breaches by over 50 % after the day work season. 

How to Enable Encryption in VoIP

 

 

 

 

 

 

 

 

 

 

 

First, you should choose a VoIP provider that supports encryption  Ensure that providers support SRTP and TLS. Because these protocols secure voice data during the transmission. 

SRTP encrypts the voice data packets during data transmission. 

VoIP system administration settings, navigate to the security or advanced settings tab and ensure the SRTP is Set as the Default protocol. 

Using TLS for Signal encryption in VOIP port. In the VOIP calls, it’s a process for call setup and tear down process. 

Enable TLS: Obtain and Configure SSL/TLS certificates from a trusted certification authority. Configure VOIP using HTTPS protocol for signaling. 

 

Configure encryption for SIP server and update user endpoints including phones, softphones and use SIPS. 

Use ZRTP for an additional media layer security. Setup VPN.

Setup VPN adds an encryption layer to all VoIP traffic. Configure the firewall and router-to-router VOIP traffic through a secure VPN. 

Keep your VoIP software and hardware updated to avoid vulnerabilities that could bypass encryption protocols. 

Update and Patch VOIP Devices Regularly. Always use tools to verify traffic is encrypted like Wireshark. These tools can help you analyze packet captures to confirm encryption. 

3. Regularly Update Firmware and Software

Outdated Software is a common entry point for attackers. So regularly updating your VoIP device and systems is very important to the communication system. Enable automatic updates if possible or schedule regular maintenance to ensure all systems are up to date.

Firmware Update:

• Firmware is embedded software that runs on VOIP devices like phones, routers, or something else gateway. More importantly, it controls how the hardware operates. 
• Updating firmware helps improve the performance of the device. Fixing bugs, enhance security, and provide new features. 
• Generally, Manufacturers release firmware updates to address vulnerabilities and optimize compatibility with other devices, which overall enhance device functionality.

Software Update:

• This refers to updating the software used to manage the VoIP network, such as the VOIP server software, apps, or desktop/phone software clients. 
• Regular software updates ensure the system is running smoothly, provide secure patches for security, and add features to improve functionalities. 

Deploy a Firewall

Use a Session Border Controller or a dedicated VOIP firewall to monitor and filter traffic. These firewalls help prevent malicious attacks. 

Understand the VOIP Security Risks

Understanding VOIP Risk is the main priority to secure VoIP communication systems. 

• SIP Trunking Attacks: VOIP Protocols like SIP can be targeted by attackers to hijack calls or perform DoS attacks. So you should think about it first. 
• VoIP-specific Malware: Another option is malware. It can exploit VoIP systems for toll fraud, eavesdropping, and data theft. 
• Call Interception: Unprotected VOIP traffic is a safety risk. It can be intercepted if it’s not encrypted. 
• Denial of Service (DoS): Sometimes,  attackers could overwhelm your VoIP system with excessive requests leading to service disruption. 

Then you have a perfect turn to choose the right firewall for your VOIP system. Then what you should do?

Choose the Right Firewall

• Hardware Firewall: If you are using physical VOIP devices like Phones, COnsider a dedicated hardware firewall such as Cisco ASA or Fortinet so that you can protect your network. 
• Software Firewall: In the reason for software, you can unlock the VoIP firewall in the PCs running VOIP software such as MondoTalk or 3CX and install firewall Software like pfSense or Windows Firewall. 
• Cloud Firewall: For cloud-based VOIp services, many cloud providers offer the integration of firewalls with advanced protection features. 

Configure the Firewall for VOIP

• Allow Only Necessary Ports: VOIP traffic requires specific ports to function. So you need to ensure first that only required ports are open for both signaling and media traffic.
  • SIP (Session Initiation Protocol): Typically uses ports like UDP 5060, and 5061 (for secure SIP over TLS).
  • RTP (Real-Time Protocol): It’s used for media like audio/video streams. Usually, it’s used within the range of UDP ports such as 10000-20000. 
• Block Unnecessary Traffic: Block all ports that aren’t needed for VOIP functionality. That way, we can protect the potential attack vectors.
• Configure NAT (Network Address Translation) for VOIP:

•  If your VoIP system is behind a router with NAT, make sure the perfect firewall is configured to correctly SIP and RTP across NAT devices. This can be done using SIP ALG or Application Layer gateway or by configuring SIP to SIP NAT and special port forwarding. 

• Use Stateful Inspection: At that time, you have to check that your system supports the Stateful Inspection or deep packet Inspection. That means it can analyze and track the state of active VOIP calls to differentiate legitimate traffic from malicious attempts. 

• Enable SIP ALG (Application Layer Gateway): SIP ALG is a feature that helps with NAT and it ensures the traversal that signals VOIP well. It’s a way VOIP traffic can pass through routers and firewalls. 

Regularly Monitor and Update Firewall Rules

• Should continuously monitor the firewall logs for any unusual activities or attacks.  It regularly updates the firewall’s role. 
• Regularly update firewall rules and make significant changes in your VoIP system.

Consider Specialized VOIP Security Tools

• Some VoIP-specific security systems can be used alongside firewalls to provide additional protections

• Session Border Controllers (SBCs): These are dedicated devices or software solutions that provide advanced security for VOIP systems that protect against attacks and manage traffic flow. 

Example of Basic Firewall Rules for VOIP

Let’s assume you are using a hardware firewall to protect a VOIP server.

1. Allow SIP signaling traffic (usually UDP port 5060):
   • Allow inbound and outbound traffic for SIP traffic on the UDP port which is 5060. 
   • If you use encrypted SIP that allows inbound /outbound traffic for SIP over TLS. 

2. Allow RTP traffic for media (e.g., UDP ports 10000-20000): Allow inbound and outbound RTP traffic through the designed media port range. 

3. Deny all other ports except for the ones needed for VOIP operation:
   • Block unnecessary ports like HTTP(80), HTTPS(443), and also FTP(21) unless explicitly needed. 

Limit Access to VoIP Systems

Restrict access to your VoIP system to authorized personnel only. Use role-based access control (RBAC) to define permissions and limit administrative privileges to essential personnel.

Use Strong Authentication

You can use a strong password that has different logs. It will be unique for administrative and user accounts in the VOIP System.  Multi-factor authentication is very important to limit access to the VoIP system. That will secure your communication system. 

IP Whitelisting: it’s very good for VoIP users that limit the access of your system. VOIP system allows the IP address that you can limit to use and authorize range to use. It helps to prevent unauthorized access to your system. 

GEO fencing: For highly sensitive systems, you can restrict access based on geographic region, blocking VOIP connections from regions where you don’t expect legitimate traffic. 

Use a firewall: Configure a firewall to allow the traffic that needs VOIP ports to configure UDP 5060 for SIP signaling. 

Set and detection systems that will monitor and block suspicious activities. 

Secure Network Access

• VPN (Virtual Private Network): At the same time, remote workers or remote offices require access to the VOIP systems through a VPN. It ensures that all VOIP traffic is encrypted and protected from interception or tampering over the public internet. 

• Dedicated VOIP VLAN: Isolate VOIP traffic from the regular data traffic that places the VOIP system in a separate Virtual Local Area Network. It ensures better control over access and improves the security system by segmenting VOIP data over access and improves. 

Limit Access to Management Interfaces

• Admin Panel Security: VOIP Management interfaces should be limited to authorized administrators when you need admin panel security. 

• Use dynamic secure protocols like HTTPS or SSH for management of the access to prevent sensitive data from being exposed. 
• Configuring the system to allow management access only from specific and trusted IP addresses. 

• Disable Unused Features: Turn off any unused or unnecessary management interface and protocols that reduce the potential attack surface. 

Implement Session Timeout and Lockouts

• Session Expiration: Set timeouts for initiative sessions. It automatically logs users out after a specified period of inactivity to prevent unauthorized access. 
• Account Lockout Mechanisms: Implement account lockout policies that temporarily disable an account after a set number of failed login attempts

Disable Unnecessary Services

• Disable Unused Protocols: We would disable unnecessary services and protocols on your VOIP system. E.G. If you don’t need to support a particular protocol like H.323 or IAX. It turns off to minimize the attacks on the surface.
• Turn Off Unused Accounts
• Regularly audit user accounts and disable or delete accounts that are no longer needed. It redirects unauthorized account access. 

Implement Network Segmentation

Separate your VoIP network from another business network to reduce the risk of cross-contamination.VLANs to isolate VOIP traffic and enhance your security system.

This isolation helps to enhance security by limiting the potential attack surface, reduces the risk of congestion, and ensures that VOIP traffic gets prioritized and handled with minimal interference.

The network segment is related to your system security, improving the performance of your system, and manageability. 

Why Network Segmentation is Important for VOIP:

1. Improved Security: By isolating VOIP traffic, you can protect the system from any threats on the network. It is useful to prevent attacks from DoS or eavesdropping. It’s great when it’s working from the scratch segment.
2. Better Quality of Service (QoS): Segmentation allows for dedicated bandwidth and traffic priority, ensuring the VoIP calls have the necessary resources and a high-quality communication system established. 
3. Simplified Troubleshooting and Management: The network segment makes it easier to diagnose and resolve  VOIP issues that isolate it from other threads. 
4. Minimizing Broadcast Traffic: Segmentation helps reduce unnecessary network broadcasts and it interferes with the VoIP traffic. Segmentation helps to reduce unnecessary network segmentation in the broadcast that could interfere with VoIP traffic. 

Steps to Implement Network Segmentation in a VOIP System

1. Identify VOIP Traffic and Critical Components

• VOIP Servers: Identify the components that handle VOIP services, such as the PBX server, SIP servers, and media servers, call controllers. 
• VOIP Endpoints: Identify all the VOIP endpoints like IP phones, Softphones, and conference phones that will interact with the system. 
• Signaling and Media Traffic: Classify the different types of VOIP traffic such as SIP and RTP. So understanding the traffic flows will help you design appropriate segments. 

2. Create VLANs for VOIP Traffic

• Dedicated VOIP VLAN: Create a VLAN specifically for VOIP traffic that is isolated from general network traffic. E.g. you could use VLAN ID 10 for VOIP and VLAN ID 20 for data traffic. Create a VLAN specifically for VoIP traffic. It isolates from general traffic. E.g. you could use VLAN ID 10 for VOIP and VLAN ID 20 for data traffic. 

• Assign all VOIP devices (e.g., IP phones, VOIP servers) to the VOIP VLAN.
• Configure your network switches to tag packets with the VLAN ID for proper routing and isolation.

• Separate Data VLAN: Create another VLAN for non-VOIP traffic like computers, printers, and file servers. It ensures these devices don’t use bandwidth which means VoIP calls 

3. Set Up a Voice VLAN for Guest or External Traffic (Optional)

• Guest VLAN for External Access: If external users or guests will access the VoIP system via remote workers and external SIP trunking providers. It creates a separate voice. 
• This external VLAN has stricter security measures and restrictions to limit the risk of attacks. It blocks the VoIP traffic from entering the internal network. 

4. Configure Routing and Inter-VLAN Communication

• Inter-VLAN Routing: Use a router and a layer 3 switch that allow communication between your VOIP VLAN and other VLANs that are VLANs. However, restricted communication minimizes exposure between VLANs. 

5. Implement Quality of Service (QoS) for VOIP Traffic

 

You can configure QoS based on:

• Differentiated Services Code Point (DSCP): Mark VoIP traffic with higher DSCP values to ensure it’s treated with higher priority by router and switches. 
• 802.1p Priority Tagging: You should use 802.1p priority tagging to prioritize VOIP packets at the data link layer for faster and more efficient forwarding through switches. 
• Traffic Shaping: Go to the door and set bandwidth limits for non-VOIP traffic to prevent congestion that could degrade the VOIP quality. 

8. Implement Redundancy and High Availability

• Dual Network Paths: this is a great path for VoIP services. It implements redundancy by having multiple paths for traffic. 
• Failover Mechanisms: VOIP traffic should be automatically rerouted to backup systems to maintain uninterrupted service at that time. 

9. Test the Segmentation Implementation

• Test VOIP Quality: After successfully implementing the network segmentation test the VoIP system performance to ensure that the segmentation is providing the intended benefits.

9. Conduct Security Awareness Training

Security awareness training for VOIP is essential to ensure the users and administration understand the risks that are associated with the VOIP System. To protect the system, we should integrate the security and integrity of communications. 

Case Study Of MondoTalk VOIP

 

1. JZ is a modnotalk client. They own a company and use VoIP for business-grade communication. It’s good! They had used among of communication systems for their business. Those weren’t unique and better communication services. Especially, It didn’t have good APIs and support systems to seamless their communication system.

Mondotalk finally offers them a good quality and seamless communication VoIP network. And it’s great because they were happy after using our system. 

2. camilleD, is a MondoTalk client. They have been using MondoTalk for a long time. Before they came to Mondotalk, it was very frustrating for their Voip network.  The quality of calls and APIs both are very important. It’s important to keep your communication system over the office or remote connectivity. Mondotalk ensures it for them. Finally, It’s a great successful Journey with MondoTalk. 

 

 

 

 

VOIP is a cost-effective and flexible communication system. it saves cost and provides better opportunities for communication at businesses. If you are in the office or at home, it’s not a problem. If you can connect with a VoIP system like MondoTalk, You will be able to connect easily to your office and work effectively in a remote location. 

 

As we know, communication is a very sensitive thing for businesses. So the security threads are common. Before using any service of VoIP companies, you should understand their quality of service and security system. Some common keys should be available such as encryption, authentication, multifactor authentication, firewall security of SIP trunk Etc.

 

 

 

 

MondoTalk’s Cloud PBX: With the Cloud PBX powering your business, you can connect your offices, located anywhere around Australia OR the world. Doing this will let you:

• Transfer calls from any office to any other office free of charge
• Answer sales calls sooner by allowing free staff in any office to answer the call
• Extend your trading hours by using offices in different time zones
• Have staff overseas or use BPO options

MondoTalk is a truly global company. We service customers in over 70 countries and are growing. With our Cloud PBX your office can be anywhere or mobil,e and our features will help give your business the competitive edge.
Please contact us for a free consultation so we can show you how we can not only save you money but also improve your business at the same time.

MondoTalk’s Cloud PABX: This video shows how easy we can make it for you to run multiple businesses from one phone. Each caller will be greeted correctly to each business. The MondoTalk Cloud PBX will let you know both before and after you pick up the phone which business the phone call is for. This gives you ample time to mentally prepare for dealing with the call thus allowing you to serve the potential client in a more professional manner.