[asterisk-users] Installed TDM02B - Problem when other end hangs up

[Stephen Bosch]

Hi, Lee:

Lee Jenkins wrote:
>> Hi everyone,
>>
>> I just installed a TDM02B and surprisingly, I had really no problems
>> except one.
>>
>> If I place an outbound call on the Zap line (Zap/3), everything works
>> fine except when the called party hangups before I do.  I do get
>> congestion, but that is expected.  However, when I try to make another
>> outbound call using that Zap line, the CLI shows that the call is
>> being dialed, but nothing happens and I get the telco's message "if
>> you'd like to make a call, hang up..." after a few seconds.
>>
>> If I call out to a party on that Zap line and hangup first, I do not
>> experience that problem.  It looks like Asterisk is not getting the
>> termination signal from the telco (Verizon) when the other party hangs
>> up first.
>>
>> Running show channels at any time after the call is disconnected (by
>> either party) shows 0 active calls/channels.
>>
>> When the problem occurs, calling that ZAP line from outside seems to
>> reset it as well.
>>
>> I'm sure it's something obvious I've overlooked, but I'd appreciate
>> any pointers.
>>
> 
> I've been working on getting this card to work correctly just about all
> day and while I'm certainly no expert, I just not sure it's a problem
> with asterisk holding the line open as others have suggested.
> 
> My reasoning follows and please let me know if I'm off base here.
> 
> 1. Attempt to dial out on zap line.  CLI says it's dialing but nothing
> happens and after a while the phone company comes back with "if you'd
> like to make a call, please hangup and try again" followed by congestion.

What exactly do you mean by "followed by congestion"? Are you sure that
the line is already clear when you dial out? (I'll bet you five bucks
it's not.)

Can you confirm that the TDM card is actually dialing? Try listening in
on the call by plugging in an extension between the TDM and the incoming
line.

Can you confirm a dial tone before the TDM card dials? You can pick up
the extension before the TDM card goes off-hook and listen for a dial
tone. The card won't care if the line is already off-hook; it should
just dial if it detects a dial tone.

Monitoring the process with an dumb extension not connect to Asterisk
would be very illuminating.

> 2. Repeat attempting to dial out as many times as I like and get the
> same result maybe every time and then out of the blue, bang! it goes
> through usually just once.  Very random and rarely can I make two calls
> in a row.  If one does in fact go through, the zap line is screwed up
> for a while after that regardless if I hang up or the other part hangs up.

IF the TDM card is actually dialing when it hears a dial tone, and the
call doesn't go through, then it's possible your DTMF duration is too
short (that is, the duration of the tone for a specific digit is so
short the switch doesn't recognize it).

Some crappy phone sets don't generate DTMF if the line polarity is
backwards, which happens more often than you might think (lots of wire
installations are done incorrectly). This isn't FCC compliant, however,
as phone devices aren't supposed to care what the polarity is. I'm
pretty sure the TDM doesn't either.

Can you show us your zaptel.conf and zapata.conf?

> 3. During the periods when I cannot dial out of the zap line, I can
> actually dial into that same line from my cell phone any time I like.
> Call after call, it goes through when dialing into the system.  Then I
> will attempt to dial out and same problem occurs: the zap line appears
> to dial out but nothing actually happens.

"Appears" and "does" are very different, as I'm sure you'll agree. You
need to find out if the card is *actually* dialing when you try and call
out.

What do you mean by "goes through" -- does Asterisk answer the call and
pass it to an extension, IVR, or voice mail? Or does the caller hear
ringing while nothing happens on the Asterisk end?

I still think the call clearing issue is at least part of your problem,
but the good news is that outgoing call issues on an available line are
easier to fix.

> My point is that if Asterisk really did have the line stuck open, I
> wouldn't be able to dial in on that same line, right?  But I can, time
> after time, but dialing out is almost always a no go.

Let's see those configs, and relevant debug log output if you can
arrange it (asterisk -vvvdc).

Cheers,

-Stephen-