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What is transcoding
There are different kinds of SIP codecs. Transcoding means translating the telecommunication signal of one technology or SIP codec into another. Depending on the SIP codec involved, more or less CPU of the gateway will be used. On beroNet VoIP Gateways, we talk about channels in order to give a better idea of the number of calls we can do depending on the codec used.
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| Codec | Type of channel needed |
|---|---|
| Clear Channel | simple |
| G.711 (with DTMF & echo cancellation) | simple |
| G.723 | complex |
| G.729 | complex |
| T.38 | complex |
| SRTP | complex |
PSTN to SIP transcoding
beroNet VoIP Gateways are often used to send calls from an analog, ISDN or GSM technology to SIP. Depending one the gateway model used and the SIP codec involved, the gateway will be able to process more or less calls. If the gateway transcodes the signal from PSTN to a SIP codec using simple channels, the number of possible calls amounts to the number of simple channels available on the gateway. The same applies for complex channel SIP codecs and the number of complex channels available in the gateway.
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| Gateway model | SBC model | FROM | TO | Nr. of possible calls |
|---|---|---|---|---|
| BF400box | BNSBC-M | BRI | G.711 | 16 |
| BF400box | BNSBC-M | BRI | G.729 | 4 |
| BF1600box | BNSBC-L | PRI | Clear channel | 64 |
| BF1600box | BNSBC-L | PRI | T.38 | 16 |
SIP-to-SIP transcoding
When a beroNet VoIP Gateway is used to send calls from one SIP peer to another two channels are established in the gateway:
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