My OBi works fine with Phonepower. To work around a strange problem (with my router and another provider), I have the following under SP2 service, which may work for you:
AuthUserName (10-digit PP phone number, e.g. 2123456789)
AuthPassword (15 Hex digit password from PP; your password format might be different)
URI 2123456789@208.64.8.6
And under ITSP Profile B, SIP:
ProxyServer: 208.64.8.6
ProxyServerPort: 12060
RegistrarServer: 208.64.8.6
RegistrarServerPort: 12060
If no luck, post all information shown in SP2 Service Status.