How many calls can I make over my T1 with hosted voice?
Posted by
Ben Rife on Fri, Feb 17, 2012 @ 02:13 PM
As a hosted voice provider, we are often asked, “Do hosted voice (VoIP) calls use a lot of bandwidth or how many calls can I make over my T1 with hosted voice?”
In VoIP (Voice over Internet Protocol) communications, it is critical that you make sure your voice traffic has priority over your data traffic (quality of service), but probably as important is the need to determine the number of simultaneous calls you can make. With VoIP, if you only have the capacity for 10 calls and someone tries to make the 11th call, they will either get a busy signal or they will severely impact the quality of the other 10 calls. To determine the number of calls possible there is a simple math calculation:
(Circuit Bandwidth Mbps * .75 * 1000) / (Voice Per-Call Bandwidth) = # Calls
Best-in-class design states that no more than 75% of your bandwidth should be used for voice traffic, so as to not starve your data traffic.
- Uncompressed voice calls (G.711) each take about 87.2 Kbps of bandwidth
- Compressed voice calls (G.729) each take about 31.2 Kbps of bandwidth
For typical circuits, this equates as follows:
So with hosted voice, even a slow bandwidth circuit like a T1 can accommodate a significant number of calls, even more than a traditional PRI, which has only 23 channels for voice.
As always, we’d like to hear from you. What other questions do you have about hosted voice or Voice over IP (VoIP)? Send me an email or reply to this blog article.