[Asterisk-Dev] Hardware details for the Digium TDM400P

[Rich Adamson]

> Does the TDM400p's FXO mode sound like a high quality device to callers ?
> 
> I ask because I've just tried to call Digiums distributors in Australia, in
> three different states. They all had the same voice response system, which I
> imagine uses Digium hardware/Asterix, and the sound was terrible - low
> fidelity and lots of clicks & crackles. 

The TDM fxo module uses a Silicon Labs chip to convert analog audio
into PCM digital bytes, which are shipped across the bus to the 
asterisk drivers. The drivers do the codec translation into g711, gsm,
or whatever "they" specified.

If the g711 codec is specified (as an example), the quality of the
audio will be toll-quality. If the codec specified is g729, gsm, etc,
the quality/fidelity will be less then g711.

The clicks & crackles are probably unrelated to which codec they
specified. It's more likely to be related to system issues, or something
else.