[Asterisk-Users] Send 12khz or 16khz billing pulse through fxs

[Andrew Kohlsmith]

On Tuesday 16 August 2005 09:12, Jeremy Salmon wrote:
> I search how to send a 12khz or 16khz to a payphone throught and FXS port.
>
> It seem that asterisk sample is 8khz but in the documentation of si3215
> (the slic of FXS module) samples rates is 16khz.
> Anyone can help me ?

Basic sampling theory -- you sample at 2x your max acceptable rate.  A 16kHz 
sine wave, when sampled at 16kHz, will appear identical to an 8kHz sine wave, 
as will a 24, 32, 40, 48kHz... 

In short: not possible.  You need something external to inject that tone, or 
you need to redesign your FXS part.  :-)

-A.