If this is a full data T1 circuit (e.g. PPP) dedicated for VoIP, then you have 1536 Kbps symmetric upstream and downstream speed. If you are going to use G.711 uncompressed speech, then you need about 87 Kbps per call with overhead. You can therefore have about 17 simultaneous calls over that connection.
If you are going to use G.729 compressed voice, then you need about 24 Kbps per call with overhead. You can therefore have about 64 calls on that connection.
For more information:
- Learn how voice compression saves bandwidth.
- Understand what compression is used in VoIP.
- Optimize VoIP over wide area networks.
This was first published in November 2005