This should do it:
Service Providers -> ITSP Profile B SIP -> ProxyServer: 127.0.0.1
Service Providers -> ITSP Profile B SIP -> X_SpoofCallerID: Checked
Voice Services -> SP2 Service -> AuthUserName: (any userid)
Voice Services -> SP2 Service -> X_RegisterEnable: (unchecked)
Voice Services -> SP2 Service -> X_ServProvProfile: B
Physical Interfaces -> Line Port -> InboundCallRoute:
{ph,sp2(Your_SIP2SIP_UserID@sip2sip.info)}
Why do you want a 2nd SIP2SIP account?
If the above won't work, defining SIP2SIP won't work either.
If you want to define SIP2SIP on SP2 you can use the same account.
SIP2SIP allows dual registration, so both the cell's softphone and the OBi can be registered at the same time.
This is the definition for SIP2SIP:
Service Providers -> ITSP Profile B SIP -> ProxyServer:
sip2sip.infoService Providers -> ITSP Profile B SIP -> X_SpoofCallerID: Checked
Service Providers -> ITSP Profile B SIP -> X_DnsSrvAutoPrefix: Checked
Voice Services -> SP2 Service -> AuthUserName: Your_SIP2SIP_UserID
Voice Services -> SP2 Service -> AuthPassword: Your_SIP2SIP_PW
Voice Services -> SP2 Service -> X_RegisterEnable: Checked
Voice Services -> SP2 Service -> X_ServProvProfile: B
Now setup a Speed Dial like this: sp2(Your_SIP2SIP_UserID)
Dial the speed dial number.
Your cell's softphone should ring.