Below are a diffrent types of Codecs that Asterisk can handle
| Codec | Speed | Simultaneous Calls over T1 (1.5 Mbps) | Notes |
| u-law | 64 Kbps | 24 | US Standard |
| a-law | 64 Kbps | 24 | European standard |
| G.723.1 | 5.3/6.3 Kbps | 289/243 | |
| G.726 | 16/24/32/40 Kbps | 96/64/48/38 | |
| G.729 | 8 Kbps | 192 | Requires license |
| GSM | 13 Kbps | 118 | |
| iLBC | 15 Kbps | 102 | |
| LPC-10 | 2.5 Kbps | 614 | |
| Speex | 2.15 – 44.2 Kbps | 714 – 34 | Open Codec |
With higher compression you can squeeze more calls through the same connection pipe, however, the savings of bandwidth does not come without a cost. The hight the compression the lower the voice quality of the call.
Zero Day IT - Peter V Nguyen 
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