Set Outbound Caller ID individually for each extension?

[Finki]

Hi there,

I use outbox.de and can set my Outbound Caller ID to what I want to. If I set it to 0123456789 the endpoint will show this number. Works fine.

But I want to show the extension. If extension 100 makes an outbound call I want to see 0123456789100.

What I have to configure? I tried serveral fields in Lines Configuration and Manage Extensions, but allways the number in field Outbound Caller ID in Line Configuration is displayed.

Does anyone has an idea?

Thanks!
Finki