[asterisk-users] Mobiles not detecting as BUSY until Dial() timeout completes

[Tony Mountifield]

In article <201603241343.24128.asterisk_list at earthshod.co.uk>,
A J Stiles <asterisk_list at earthshod.co.uk> wrote:
> I'm not sure if this is an Asterisk thing, a handset thing or a telco thing, 
> so please be gentle with me if this is not the right place to ask .....
> 
> When placing a call over a SIP channel to a mobile phone, if the phone is 
> engaged, it does not return a BUSY status straightaway.  Rather, I get a 
> ringing-out tone for the timeout duration specified in the Dial() statement; 
> *then* I get ${DIALSTATUS}=BUSY.
> 
> Now, given how far we have moved on since the days of clicky-clicky exchanges, 
> it is entirely possible that the mobile phone implicitly supports multiple 
> "lines", so you can put an existing caller on hold, talk to the new caller and 
> then switch between them as long as they stay on the line .....  in which 
> case, this behaviour is pretty much what should be expected -- Asterisk 
> doesn't know for sure that the remote party really is engaged, because they 
> retain the option to put their call on hold and answer you, so it lets the 
> timeout run; then, since they were already on a call at the time the first 
> signalling message was sent, it sets the dialstatus to BUSY.
> 
> 
> Where should I be looking, if I want to reproduce the "old-fashioned" 
> behaviour and return an engaged signal straight away?

Sounds like the mobile line has Call Waiting enabled, and the waiting call
has been ignored by the recipient until it times out.

See https://en.wikipedia.org/wiki/Call_waiting and try *#43# on the mobile
in question to check whether call waiting is active. Use #43# to try
deactivating it and see if that helps.

Cheers
Tony
-- 
Tony Mountifield
Work: tony at softins.co.uk - http://www.softins.co.uk
Play: tony at mountifield.org - http://tony.mountifield.org