Voip provider with extension

Hi All,

I have setup to my asterisk towards pennytel my VOIP provider. Registration seems to be successful.

I also have some extensions hanging off my asterisk box. So I register my extension with asterisk. Then using the number I have setup in my dial plan, I ring, with the hope that it will make an outgoing call using my voip provider. The sip messages look to be ok with Ringing etc. But then I get a 603 decline from my VOIP Provider.

It looks like in the FROM tag, asterisk uses the extensions sip uri, but I want it to use the penntel sip uri. Is that possible?