[asterisk-users] Restricting transfers between SIP phones

[Philipp von Klitzing]

Hi!

> > So, does anyone know of a way to detect whether a call from a SIP phone
> > is the first step of an attended transfer or an original call?  

It could probably work if you put a SIP proxy in between (ref. Kamilio).

> The only way to achieve what you want is to never allow a call to a
> different department when the same phone already has a call on hold.
> This will however stop the (in some places quite common) practice of
> calling the other department to ask a quick question, then returning to
> the original caller.

Workaround: Have a second SIP account on the phone which must be used if 
you call the other appartment.

> It could be somewhat tricky to implement as well, but it should be
> doable with call-groups.

With SNOM phones you could use an "Action URL" to catch phone-based 
attended or blind transfer actions. The called URL can then trigger 
anything you like on your server.

Philipp