I'm using Kamailio as dispatcher to a FreeSwitch setup.

Currently it "almost" work. I have 2 extensions connected to my FreeSwitch via Kamailio. However, I can only send calls one way because Kamailio seems to change the domain on the extension.

One extension is registered with ID@sip.my-domain.com. This I can send calls to.
The other extension is registered with ID@local-ip. This I cannot send calls to.

Isn't it possible to have Kamailio register the extension on my FreeSwitch with @sip.my-domain.com?

If I register both extension directly to my FreeSwitch everything works.