Dahdi Hanging up before able to answer

I have a TDM400P and for some reason one line, actual phone line, not the spot on the card, doesn’t want to work correctly. If I plug an old school phone into that line it works every time. If I plug it into any port of the TDM400P it only works about 1 every 6 times. I can see the call coming in on the dahdi line but then it stops. On the phone I’m calling into this line on, it rings once and then is silent until I hear the click. Any ideas or thoughts of how I can figure this out. It must be something inside this system because if I plug the line into a normal phone, it works 100% of the time. Thanks for your help.


I have the repair man coming out! I’ll keep you posted.

Correct. You can answer a POTS line with just a pair of earbuds. it just doesn’t work very well.

So the fact that I plug an old school phone in and it works fine doesn’t rule out that sort of problem?

There are many parameters to an analog PSTN line, dahdi does it’s best to use sane and common parameters but sometimes your line might be out of “spec” on battery voltage, line loop current and a whole bunch of other parameters, from the code

module_param(debug, int, 0600);
module_param(loopcurrent, int, 0600);
module_param(reversepolarity, int, 0600);
module_param(robust, int, 0600);

module_param(opermode, charp, 0600);
module_param(timingonly, int, 0600);
module_param(lowpower, int, 0600);
module_param(boostringer, int, 0600);
module_param(fastringer, int, 0600);
module_param(fxshonormode, int, 0600);
module_param(battdebounce, uint, 0600);
module_param(battalarm, uint, 0600);
module_param(battthresh, uint, 0600);
module_param(ringdebounce, int, 0600);
module_param(fwringdetect, int, 0600);
module_param(alawoverride, int, 0600);
module_param(fastpickup, int, 0600);
module_param(fxotxgain, int, 0600);
module_param(fxorxgain, int, 0600);
module_param(fxstxgain, int, 0600);
module_param(fxsrxgain, int, 0600);

all of which can be overridden as you load your modules, but I suggest you need to call “repair” and have them check that your trunks are properly provisioned at your premise, and there is no problem with the “local loop” compared with your other non-problematic trunks.

Turns out port 3 on the card is bad. Switched to port 4 and everything worked fine. Thanks for the help.