here´s the setup:
I get a call from pstn.
When a call comes in I add a zero as prefix (this is needed for call back.).
This is done in extensions_custom.conf
everything works fine.
but sometimes I need to forward a call through a SIP trunk into another SIP PBX.
I thoght I could create a trunk-custom thing in the extensions_custom.conf where I remove the prefixed zero from the Caller ID Number when a call is established through this sip trunk.
But I don´t get it to work.
(the other SIP system don´t need the 0 as prefix).
The other PBX system is “dumb” so I have no chance to remove it there.