Fixing broken voice on VoIP.

Follow these step by step instructions for fixing broken voice or choppy voice on your VoIP calls.  Typically broken voice on VoIP phone connections come from insufficient bandwidth, or a connection whose bandwidth is being grabbed by other applications.  Correcting broken voice (choppy voice) is a systematic process of testing the bandwidth and then focusing on reserving enough bandwidth for each VoIP call.

Step 1 measuring Internet bandwidth.

Measure the actual bandwidth available from the Internet provider.  This can be done by using a speed test from a PC in the LAN.  Complete a 2nd test, a tweak test, that will show some important information, including if the MTU on your router may be set too low.

• Using the results make sure that you are getting close (at least 80%) of your ISPs level of service of the upload and download speeds.  Understand that you need approx. 100kbps for both the upload and download for each active call.
• Adjust MTU settings on your router if not close to 1500.

Bandwidth too low:

• If less than 80% work with ISP to improve the service.
• If ISP is delivering close to level of service, but that capacity is not great enough to support VoIP and PCs adequately, order a larger bandwidth service.  Change VoIP lines to G729 instead of G711 for less bandwidth usage.

Bandwidth adequate:

• Make some test calls with PC's off and on, preferably using the applications that typically get used.

Broken voice when other applications (PCs, gaming consoles) are being used:

• Proceed to step 2.

Step 2 setting QoS for VoIP on router.

Having made some test calls and found that broken voice occurs on the VoIP line and other applications are in use, set QoS (Quality of Service) for the router so that voice (RTP) will have priority.

• Using the bandwidth measurements found in step 1, set up QoS on your router.
• For larger networks setting up VLANs for voice should be considered.