VoIP uses your Internet data connection so its important you have adequate bandwidth or internet speed. You can save bandwidth by using more efficient codec's (Audio Compressors) in the settings of your hardware or softphones, but the most common default standard is a codec called G711. This gives 80 Kbps sound quality - the exceptional quality we think you'll want! Alternative codec’s like g.729 can reduce bandwidth requirements over the industry standard g.711 by as much as 50%, but reduce the call quality to 40 Kbps.

So in bandwidth terms, you will need to have at least 80 Kbps (40Kbps for G729) of upload speed and at least 80 Kbps (40Kbps for G729) of download speed per concurrent phone call.

Your download speed will likely be substantially more than your upload speed, so upload is the key constraining measurement to take a good look at. 

You can check your internet speed on our website: http://www.vantact.com/support/speed-test/