Most Common SIP Problems and How to Fix Them


A SIP trunk is essential for businesses that are looking for a more efficient and modern phone system. But despite its upgraded capabilities, users can sometimes experience problems when using and implementing SIP trunking. To help users alleviate these issues, we’ll discuss common SIP problems as well as SIP trunk troubleshooting!

Related: Try global SIP trunking solutions risk-free

One of the best things about SIP trunking is that you can keep your existing communications infrastructure - and that includes your phone numbers. If all goes well, outgoing carriers and your provider can work together to move your numbers in two weeks or less. But in some cases, you may experience a longer wait time for your numbers to be completely ported over.

You can usually address this issue by working directly with your carrier and your SIP trunk provider to move the process along as quickly as possible.

Setting Your System Up For Simultaneous Calls

When you’re moving to a SIP trunk, it’s important to evaluate the number of call paths, or SIP trunk channels, that your system will need. If you don’t, you may experience issues when you’re trying to make simultaneous calls on your system.

Although this is one of the most common problems with SIP trunking, it's also easy to fix. You can address this issue by ordering the number of call paths you’ll need to handle the total number of concurrent calls that your business handles during your busiest hours.

Choppy, Laggy, or Jittery Calls

If you’re experiencing choppy or lagged calls with your SIP trunking service, you may not have an adequate amount of bandwidth available on your Internet service. Because VoIP runs entirely over the Internet, it’s essential that you work with your Internet provider and your SIP trunk provider to ensure that your system can handle each of your incoming and outgoing calls.

If you're curious about how much bandwidth is needed to support high quality calls, you can use this simple equation:

Number of Concurrent Calls x 85 kbps = Required Bandwidth

Below is a rough estimate of how many concurrent calls you can have with your given bandwidth:

voip call bandwidth calculator

Keep in mind that some codecs might require more than 85 kbps per call. However, most SIP providers use the G.711 and G.729 codecs, which usually require anywhere from 85 - 100 kbps to handle a single call.

If you have more than enough bandwidth and are still experiencing choppy or lagged calls, it may be time to take a look at your Quality of Service (QoS) settings. QoS allows you to prioritize certain types of traffic, such as voice calls, on your data network. Since other forms of data are not time sensitive, you can adjust your QoS settings to always put voice traffic first. You can change your QoS configuration on your router. By setting your router to prioritize VoIP traffic, you can greatly cut down on poor call quality.

Before we go into detail about the different types of codecs SIP providers typically use, here are a few things you need to know:

  • Bitrate per second: the rate at which bits of data is transmitted in a given amount of time
  • Lossless compression: Lossless compression rips your audio file so it is greatly reduced in size, but no quality is lost. In other words, it is a perfect copy.
  • Lossy compression: Reduces the file size up to 10x, but some audio data is permanently lost, so audio quality might be slightly compromised.
Codec name Average bandwidth required Description
G.729 8 Kbps 24 Kbps Uses an algorithm for extreme compression, works well with low bandwidth
G.711 64 Kbps 80 Kbps Offers lossless compression to reduce bandwidth needs, can be used for faxing as well
G.722 48-64 Kbps 80 Kbps High quality, but requires more bandwidth
G.726 16-40 Kbps 56 Kbps Used in international trunks
G.728 16 Kbps 32 Kbps Offers toll voice quality for lower bandwidths

Other Common SIP Problems

This list is by no means exhaustive, as some other problems may arise. Here are a few more common SIP problems and some SIP trunk troubleshooting tips:

  • Audio delays: In addition to choppy calls, audio delays may cause problems with your SIP trunks. Some possible explanations for this could be interference from headphones/VoIP hardware, splitters or caller ID devices, and plain old bad equipment.
  • Codec mismatch: Sometimes when setting up SIP trunks, you may accidently use the incorrect codec. Get with your SIP provider to ensure the proper codec is being used.
  • Bandwidth issues: Having not enough bandwidth is a pretty common issue among SIP users. Reach out to your internet provider if you see bandwidth issues and talk to them about upgrading your internet service plan.

Solving Problems with SIP Trunking

As you can see, problems with SIP trunking are easily addressed by setting up your system correctly and working closely with your provider. If you experience any of the problems above, use our recommended tips or contact your provider for more assistance.

Looking for additional resources and information about SIP trunking? Check out the related article below: