This article describes the bandwidth requirements for VoIP and how different codecs affect bandwidth usage. It also provides guidelines for ensuring optimal call and fax quality by managing your internet speed and bandwidth effectively.
Bandwidth used for VoIP is determined by the codec used to convert an analog voice/fax signal to digital data packets. UNIVERGE BLUE® uses a codec called Opus for voice calls by default.
Additionally, four other codecs are supported:
- G.722 (Used for some voice calls where the other telephone carrier does not support Opus).
- G.711u (Used for fax).
- G.729
- G.711a
Note: Proper internet speed is critical for the quality of your VoIP calls. However, 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 excellent call and fax quality. Even 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 phone calls to drop, audio to cut in and out, faxes to fail, and many other call or fax-related issues.
Example: If you have three phones, one fax adapter, and one computer, you need (3 phones) × 90Kbps + (1 fax adapter) × 100Kbps, which requires:
- 370 kbps download minimum needed
- 370 kbps upload minimum needed
- Use these numbers to then set up Bandwidth Management on your router to stop your computer from using all the bandwidth.
Check your speed through our test servers. Use this Bandwidth Tester to test your bandwidth.
Use these bandwidth numbers to set up Bandwidth Management (BWM) to ensure excellent call quality. The steps to set up 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 set up BWM, contact your IT department or the manufacturer of the router for instructions.
For more information on audio quality issues, review this Call and Fax Quality Issues (QoS) article.
For more information on Bandwidth Management, review this Preventing Call & Fax Quality Issues with Bandwidth Management