intraworks,
If that is the URI that you want to point to you don't need SIP Adaption for that. IF you need to change where you say you are coming from is reg-gw.sip.global then you will need to do that with SIP Adaption.
To change where you Register to, i.e. the Registrar, then that is under the Voice Network Element for your SIP Peer Element under SIP Registrar FQDN or IP Address field.
Thanks,
TE