Bandwidth used for VoIP is determined by the codec used to convert an analog voice/fax signal to digital data packets. Intermedia uses a codec called G.729 for voice calls by default. Also codec G.711 is used for fax and some voice calls where the other telephone carrier does not support G.729. Another codec we support for voice calls is Opus. Having the proper internet speed is critical for the quality of your VoIP calls. 

Note: speed alone does not guarantee optimal results for VoIP. The minimum internet connection speed required for VoIP is between 90 kbps to 156 kbps.

Your phones need a consistent, reserved amount of bandwidth for an excellent call and fax quality. Even just one computer on an internet connection with fast bandwidth speeds can use all of the bandwidth in bursts or frequently, depending on what you are doing on your computer. This creates a bottleneck that causes your phones calls to drop, audio to cut in and out, faxes to fail, and many other call or fax-related issues.

Example: you have 3 phones, 1 fax adapter, and 1 computer = (3 phones) * 90Kbps + (1 fax adapter) * 100Kbps, which requires:

  • 370 kbps download minimum needed
  • 370 kbps upload minimum needed
  • use this numbers to then setup Bandwidth Management on your router to stop your 1 computer from using all the bandwidth   

You can check the minimum requirements for your environment with Bandwidth Requirements Table.

You can check your speed through our test servers. Please click here to test your bandwidth.

Make sure to use these bandwidth numbers to setup Bandwidth Management (BWM) to ensure excellent call quality.  The steps to setup BWM vary depending on the router. However, our Recommended Routers all have BWM and have instructions on how to set it up.

If you do not have a Recommended Router and want to know how to setup BWM, please contact your IT or the manufacturer of the router for instructions.

Review these articles for more information on audio quality issues - Call and Fax Quality Issues (QoS), and Bandwidth Management - Preventing Call & Fax Quality Issues with Bandwidth Management.