Modify CID when redirecting a call through a trunk


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.

The route to the dumb pbx system uses a trunk you defined on your system right? Take a look at the dialing rules for the trunk you can create a removal dial pattern (to see the format cursor over the words “Dial Rules:”).

Thank you very much for the quick answer,

but with the dialing rules and pattern i only can modify the dialed number and not the original callers ID number.
Or did I missed something.

no you are right I missed it. I flipped the problem in my head.

any tipps?

thank you.

thank you