asterisk users - Sep 2006 - How to detect dial tone on ZAP channel before dialling using TDM2400P

Hello all

I have an asterisk box running Asterisk 1.2.8 and I installed a digium
TDM2400 with 8 FXO ports. When I amke a call to the PSTN, the zap channel
answers, and teh call goes through if a PSTN is connected to the answered
port. However, if there is no dial tone in the answered channel, or if no
POTS line is connected, the user gets no indication until the call time
outs. I want * to be able to detect if there is a dialtone on the channel,
before it dials, if not, to send a busy signal or choose another available
channel.

Thanks.
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Naija Man wrote:
> Hello all
> 
> I have an asterisk box running Asterisk 1.2.8 and I installed a digium
> TDM2400 with 8 FXO ports. When I amke a call to the PSTN, the zap channel
> answers, and teh call goes through if a PSTN is connected to the answered
> port. However, if there is no dial tone in the answered channel, or if no
> POTS line is connected, the user gets no indication until the call time
> outs. I want * to be able to detect if there is a dialtone on the channel,
> before it dials, if not, to send a busy signal or choose another available
> channel.
Asterisk does not support this on analog ports.