[asterisk-users] Problem with busydetect and cell phones

[Stephen Bosch]

Ryan McDaniel wrote:
>> I have a very strange problem I'm hoping someone has encountered
> already.
>> I've scoured the internet for an answer to this one.  My phone company
>> provides no disconnect supervision.  Hence I'm forced to use the
> busydetect
>> feature.  I have a TDM400 with two FXO ports.  If I call from an
> internal
>> extension to a landline and then hangup the landline Asterisk detects
> the
>> busy signal correctly and clears the line.  If I call from an internal
>> extension to a cell phone and then hangup the cell phone Asterisk will 
>> never
>> detect the busy signal though it is clearly there.  Asterisk will
> happily
>> sit there listening to the busy signal.  I suspect that the busy signal
>> styles are slightly different though it is undetectable to me.  How can
> I
>> fix this???  It causes severe issues when a call is forwarded to a cell
>> phone via the Zap interfaces as once you hangup the cell phone Asterisk
>> never releases the channel.
>>
> 
> The landlines are with AT&T.  The cell phones I'm testing with are
> Cingular (AT&T subsidiary).  There must be a subtle difference in the
> busy signals.  How can I make it catch busy signals from both carriers?

Have you tried calling AT&T and asking for call disconnect supervision?

I realise that this can be a thankless and tedious endeavour, but it IS
worth trying. There are almost no commercial switches that don't support
this; it's a matter of activating it for the specific circuit in
software. Particularly if you have a business line -- you can demand it.
All PBXs need it if they use analog lines (and plenty still do) so I'm
sure this is not an alien concept to AT&T. It's just a matter of finding
the right Earthling there who can help you.

This might be one of those times where a "beer with the technician" will
get you some joy, if calling Repair doesn't give you any joy.

-Stephen-