CallerID send before ring

Hi Dears

I have a PSTN line that send CallerID before first ring and i can’t receive callerid.
I search about this problem but unfortunately i found that asterisk can’t detect callerid if it send before first ring
I use asterisk and dahdi
is there any way for solving the problem???


At least for some FXO interfaces, Asterisk can handle BT style caller ID. I don’t have FXO cards, so I don’t know the details, but the BT system sends a line reversal before the caller ID. (cidstart=polarity)

If your PTT doesn’t comply with the BT SIN, you will need to provide more information, like the identity of the PTT, or, at least, the country.

What combinations have you already tried?