[asterisk-users] Hang up detection with TDM400P and Telewest/Virgin Media line

[Gordon Henderson]

On Thu, 9 Oct 2008, Mike wrote:

> Zaptel Version: 1.2.11
>
> Asterisk 1.2.13
>
> I called my mobile from the line and hung up.  The line just went
> silent.  There were no tones.  I also watched the lamp on the phone, it
> didn't got out.  I guess this could be because the line current isn't
> dropped or maybe because of capacitance in the phone?

> I tried this on my BT line and when I clear down, the lamp on the phone
> goes off momentarilly and then I get a single, continuous tone.

I'm guessing this lamp is on an ordinary analogue phone you have?

> Gordon, would you mind doing this test on your line to see what happens?

OK. A bit convoluted this as I'm not local to the PBX, but an IAX trunk, 
another asterisk and a SIP phone away from it - however I'm looking at 
verbose console output on the original asterisk box which has an OpenVox 
card (TDM400 clone) so:

Telewest line <-> TDM <-> Asterisk <-> IAX trunk <-> Asterisk <-> SIP phone

I call into the site on their Telewest landline from my mobile (O2). My 
phone rings, which is to be expected.

I don't answer it, but hangup my mobile.

I can't tell if telewest have dropped the line immediately, but from 
asterisk point of view, the line stays "open" for about another 2-3 
seconds, then hangs up and asterisk detects it and stops the phone 
ringing. As far as I can tell, this is all perfectly normal, and it's what 
I see with BT lines too.

If I answer it, that's fine too.

If I then hangup the mobile, the (analogue) line hangs up almost 
immediately, this is detected almost immediately by asterisk and it clears 
down the call.

So that's more or less what I'm expecting.

Going the other way: Dialled out from my SIP phone to my mobile - when I 
hungup the mobile the call dropped almost instantly and my SIP phone 
hungup.

So again, that's more or less what I expect.

> If not, I'll try to get hold of someone with a Telewest phone and get
> them to try it.

I've heard that Telewest used whatever switch they could get their hands 
on at the time when they were building their network, and that different 
regions might well have different equipment in the TW exchanges. More 
complicated by them buying up the local cable co's (eg. Eurobell in the 
Plymouth area where this line is), then being sucked into the ntl: monster 
and now virgin media.

> I'm trying to work out what to expect from the line and see if that is
> consistent with what I am seeing.  Once I know what the phone line is
> meant to do, then I can work out if it is doing and what I can do with
> Asterisk to accomodate it.

Good luck!

Gordon