Not sure what the issue is and where to start , need help to trace the problem

I have installed a freepbx on rhel 5 server running asterisk
I have setup a Soft vonage phone, incoming calls and outgoing calls to any vonage phone works perfectly, incoming call from mobile or any BT landline works perfect… But when i try calling any mobile or BT landline, the third party gets ring and as soon as third party picks the call, the call drops from third party side where as the call status is connected on my side.
now sure where i am going wrong.

Really appreciate if some one call really lead me how to troubleshoot this issue.

many thanks

What country are you in?

When you call someone first the zaptel card presents a “loop” to the telephone exchange, electricity flows on the circuit (it goes down from about - 50 volts to -12 volts due to the current flowing) and the exchange knows you are making a call.

Then when you hang up the phone, the Zaptel driver knows to clear down (hang up) the call by disconnecting this loop - the line voltage goes up to -50 volts again and the line is free for incoming calls to arrive.

When someone calls you and they hang up first, its easy for a human to realise this (as there is silence or a warning tone) but electronic equipment (including conventional PBXs and answering machines) gets confused and will keep the line seized (off the hook) unless there is an extra signal to show that the calling person has cleared.

This signal is usually at least one of these things (sometimes you get all of them!)

  1. a disconnection of the electric current on the phone line (it goes to zero volts) for 0.1 - 0.8 seconds

  2. a reversal of the polarity of electric current on the phone line

  3. a tone - in US it is often busy or a reorder (fast busy) and in England it is a constant tone of 400 Hz

Number one is best for standard Asterisk line cards, provided the signal is long enough. I had to get my local telephone company to set it to 800ms so that it was picked up reliably.

But not all phone lines have this signal.

It is usually called a CPC signal in US, in Britain is it called Disconnect Clear. One way to test for it is to get a cheap Chinese telephone with illuminated keypad. The sort that cost a few dollars in what I think you chaps may call a “downtown store…”

Then call your line, hang up and watch the keypad at the same time. If the keypad flashes, you have this signal.

if you don’t you may need to get the telephone company to activate it, or if it is there but too short they may have to set it to the right length (whatever Sangoma also recognise).

A workaround for US users is to get Asterisk to detect the busy signal - but this can cause other problems such as false clearing in the middle of calls - also there is a hardware box to generate CPC from a reorder or dialtone…

Also, what version zaptel are you using? there was a really bad one ( which caused all manner of problems of this nature…

If this does not work then it has been known that some telco’s place the hang-up detection signaling on the line shorter then the standard. So to allow our card to pass a smaller hang-up detection signaling through you can change the following value in /etc/wanpipe/wanpipeX.conf (x being the wanpipe number).
If 4 works then you can try increasing this number and see which one works best for your line. If you go much lower then 4 then you could get false hang-ups.

have a look in /var/log/asterisk/full around the times these odd “calls” are occuring… it may show any odd line conditions like polarity reversals, battery alarms…

Check out:
As well as:…ig+zapata.conf
Look for the busydetect=yes section

Also use asterisk -rvvvv to give you some debug messages to look at.

Isn’t asterisk beta?

It just looks relevant and I had the cut and paste in one of my notes.