asterisk users - Mar 2009 - Set origin CallerID when forwarding calls to mobile phone

Hello,

I've just installed the current trixbox-Version; calling from and to
outside via sipgate (germany) works well; internal calls too.

But I have set up an ring group with an external member (mobile phone)

When calling to this ring group, the CallerID of my sipgate-Account is
shown and not the origin-callers-id.

Sipgate allows me to set the caller id, but how can I set it
"dynamically" for forwarded calls?

Any ideas?

Regards,

Philipp