[asterisk-users] Custom Pickup and Transfer dial string

[Marcello Lupo]

Hi to all,
i already searched the archive without finding a solution to my problem.
I have asterisk installation 1.2.18 to support multiple virtiual PBXs.
I use SIP peer in the format <ID>-<EXT> to let every virtual PBX to  
share the same numbers of EXT.
Ex.

(PBX ID 10 Extensions)
10-101
10-102
10-103

(PBX ID 20 Extensions)
20-101
20-102
20-103

I use some rules in the dialplan to let users of this pbxs to dial  
only EXT to call other extensions of their PBX.
So i add the pbx ID statically to the called number if it is an  
extension.
Now i have to realize the pickup call and blind and attended call  
transfer.
As i read in the documentation the standard codes *2 for transfer give  
me the dial tone to dial the extension to
transfer at but i need to transfer the call not to the EXT but ID-EXT .
Have you any idea on how to realize this for Pickup and call transfer?
The end users don't have any idea of the ID part of their extension so  
i have to let them dial something like *2101 and
transfer the call to 10-101 . For the pickup i need them to dial  
something like *8101 and answer the call ringing for 10-101.
I already thought a solution for the Pickup to use the application  
Pickup joined to a custom pickup code and a custom string in
the command it self, but i dont have a solution for the call transfer.
Thanks in advance for help.
Bye,
Marcello