[asterisk-users] Correct voltages but no dial tone on TDM2400P

[Alex R Green]

A big G'day to everybody on the Asterisk list.

I am having a lot of trouble getting the TDM2400P card working in 
asterisk. I will give the important details below, please let me know if 
I am doing anything obvious or ideas for debugging this.

SUMMARY:
I get the right voltages on the line with the phone on or off the hook, 
but no dial tone, no ringing in or ringing out.

INSTALLATION AND ZAPTEL HARDWARE:
CentOS based `Trixbox CE' 2.3.0.1. It has Asterisk 1.4.6.
The TDM2400P card has three green FXS modules close to the 50pin 
connector and three red FXO modules at the rear. The card was installed 
in the system prior to loading Trixbox. I think the card is working: 
zaptel.conf was set up correctly with the first 12 channels fxsks and 
the last 12 channels fxo kewlstart. zttool shows the TDM2400P with no 
alarms, internally clocked, 0, 0, 0 24/24/0. When I take the phone of 
the hook the 'Total/Conf/Act goes' to 24/24/1. When I "cat /dev/zap/24" 
with the phone off the hook, I get random data, and talking into the 
phone or hitting keys changes this data, indicating the TMD's adc is 
working.

PHONE CONNECTION:
The Tip is connected to Pin2 on the 50pin Centronics, ring is connected 
to Pin27. Ring is 46V below Tip on hook and 6.7V below off hook.
Is this the right connection for channel 24?
Why is there no dial tone coming through?

ASTERISK:
On the Asterisk side, I can set up sip phones and trunks, but no matter 
how hard I try, I have no luck with the analogue phone. Currently 
zapata.conf is set up as follows:
context=internal
signalling=fx0_ks
channel => 24

Any pointers would be very much appreciated,
Cheers -alex