SIP Testing for Beginners: 7 Quick Checks and 5 Free Tools

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If you’re used to having choppy or even dropped calls when using a VoIP phone, you know how frustrating it can be to have connectivity issues.

That’s why running Session Initiation Protocol (SIP) tests can be very helpful for any organization using VoIP. They provide a simple way to make sure your connection is stable, secure, and instantaneous when using your VoIP phone—meaning fewer headaches and less time spent scrambling to get help from your tech support team.

And the best part? You don’t even need to be particularly tech-savvy to do some basic SIP and VoIP testing. With various quick checks and tools, you can ensure that your VoIP calls can occur without any issues.

Graphic to illustrate how SIP-based telephony works.

7 Quick Checks for SIP Testing

Performing some simple actions can evaluate the stability of your SIP connection easily and accurately. Here’s a look at several of them in detail.

Disable SIP ALG

One quick check for SIP testing is to disable the SIP ALG (Session Initiation Protocol Application Layer Gateway).

SIP ALG is a default application enabled by many commercial routers to prevent various problems caused by router firewalls, which it does by monitoring and potentially modifying VoIP traffic. Because of this, SIP ALG can often cause a number of issues when using VoIP, some of which include:

  • Lost connections: When SIP ALG is enabled, it’s easy to be completely disconnected during a VoIP call
  • Poor call quality: As SIP ALG can modify calls, quality issues such as static noises and echoes are common
  • No way or one-way audio: Due to SIP ALG modifications, one party on a VoIP call may be unable to hear the other, while sometimes neither party will be able to hear despite technically being connected
  • Failed registrations: Failure to connect is another common result of having SIP ALG enabled
  • The phone keeps ringing and can’t be answered: A phone that constantly rings but isn’t capable of being picked up is often due to SIP ALG

All of these problems are telltale signs of SIP ALG issues during a VoIP call, in addition to lapses in audio transmission and other call quality issues. Due to the many problems that SIP ALG produces for VoIP users, it can be better to disable it when using a VoIP phone.

Fortunately, this is easy to do and can be accomplished by following a few specific manufacturer instructions for your commercial router.

Test your connection

In short, if your connection doesn’t meet the recommended VoIP network requirements, you’re going to run into problems.

Conducting early tests of your internet connection’s capacity is worth it because a slow or poor connection will likely result in dropped calls, connection failures, and other VoIP call quality issues.

In particular, upload and download speeds are important since a real-time connection between VoIP callers requires sending and receiving packets of audio data. If your connection is hampered by slow and inadequate speed, your call quality will likely be affected.

The good news is that testing your connection speed can be done with a few simple online tests, many of which are free and simple to use. The free Nextiva speed test, for example, tests your connection speed and quality by simulating up to 200 VoIP lines.

Double-check your username and password

A quick and simple test is to make sure your username and password are correct by logging out and then back in.

An incorrect or outdated username or password will obviously slow down and often outright prevent you from accessing your VoIP and making calls. However, by keeping your correct password and username on hand, you can avoid these problems entirely.

Check your provider status

Another quick check is to check your provider status.

If you have questions about your SIP connection or quality, reaching out to your provider is a simple and effective way to ensure it’s working well. If you uncover any problems, ask your provider about the next steps to address them.

Test your server connection

Server issues are another reason for SIP connection issues.

Fortunately, server testing can be done pretty easily in most cases by following your provider’s specific instructions. Contacting them directly is always a good way to get information about your server’s status.

Check your router

It’s always a good idea to check and troubleshoot your router as part of a SIP test too.

If you’re having trouble connecting or have experienced VoIP call quality issues, check your router carefully for any problems. Resetting it can help, as well as contacting your provider for additional information on improving your connection.

Look at your Call Detail Record (CDR) for errors

Finally, another quick check for SIP testing is looking closely at your CDR to try to pinpoint any errors.

A CDR contains a detailed log of your phone activity. By checking it carefully for any errors and problems, you can potentially pinpoint any connection issues you’re experiencing. Contacting your provider for assistance and more information about how to do this is also a good idea.

5 Free Tools for SIP Testing

In addition to running some quick checks, a number of free SIP and VoIP testing tools are available. Many (if not most) of them are also simple to use.


One of the best and most popular SIP testing resources, Wireshark is a free and open-source network protocol analyzer that’s commonly used for SIP testing and troubleshooting.

Wireshark works via a method called packet capture, which lets you browse the data packets and traffic on your network for any potential problems. When used for SIP testing, Wireshark can intercept, analyze, and diagnose problems with VoIP calls, making it quick and easy to identify any connection issues. This tool is also fairly beginner-friendly, as it’s relatively easy to download, install, and use.


NetworkMiner, like Wireshark, is a free and open-source packet analyzer tool that works well for SIP and VoIP testing and troubleshooting.

Designed for investigative analysis, NetworkMiner is also beginner-friendly and lets you take a deep dive into the data you’ve captured, making it a great tool for in-depth analysis of your VoIP.

Colasoft Capsa

Colasoft Capsa is another easy-to-use testing and troubleshooting tool for VoIP and SIP.

It’s a comprehensive network analysis tool that provides real-time monitoring, packet capture, analysis, and optimization features—which are all useful for diagnosing SIP and VoIP connection issues. The tool is available in both free and paid versions and also offers a user-friendly dashboard, extensive data analysis, and the ability to support more than 1,800 protocols and sub-protocols.


SmartSniff is a Windows-based free packet sniffer tool that includes detailed packet analysis features for SIP and VoIP testing.

Free to use, SmartSniff is similar to Wireshark in many ways and is one of the most beginner-friendly tools available due to its lack of a query language. For users who are real beginners to the world of SIP and VoIP, SmartSniff is one of the top options out there.


EtherApe is a free resource that can run on Mac OS, Linux, and Unix.

It works by using network maps and packet capture features to analyze vast amounts of data in real time. EtherApe offers excellent privacy protection and the ability to track both wired and wireless traffic, making it useful for many SIP and VoIP testing scenarios.

SIP Test for a Better Connection

SIP issues can be frustrating, but with basic checks and free tools, you can easily test your SIP connection to make sure that it’s working properly. Even if you’re a beginner in the world of SIP and VoIP technology, there are many resources out there to help you ensure a strong VoIP connection and combat any technical errors.

If you’re in the market for a new business communications solution, check out our list of the top VoIP providers and you can probably avoid a lot of these problems altogether.

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