[asterisk-users] How to detect dial tone on ZAP channel before dialling using TDM2400P

Eric "ManxPower" Wieling eric at fnords.org
Wed Sep 27 15:52:51 MST 2006

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.

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