[Freeswitch-users] Sip profile help

I'm new to Freeswitch so if this has been discussed, please send me to the proper link. I need to setup a trunk to Level3 (I've heard that's not popular at Freeswitch too :) ) Level3 does not use authentication but restricts based on IP address. When I setup the SIP profile, the username and password fields are required so I put in anything and set register to false. Whatever I put in the username field gets passed to Level3 as <username@xxx.xxx.xxx.xxx> in the FROM, Contact, and Remote-Party-ID fields. I've tried putting in nothing, but then I get <null@xxx.xxx.xxx.xxx> instead. How do set this to the E164 number of the calling party instead of the username?