After authentication, the S-CSCF should send a SAR to the HSS. In the response, there should be a Cx-User-Data AVP which contains a XML document with the IMS data for the subscriber. As a starting point, you could provision a single InitialFilterCriteria with no TriggerPoints, and a default ApplicationServer which will handle all SIP methods.
Here's a simple working example from my test bed:
<?xml version="1.0" encoding="UTF-8"?>
<IMSSubscription>
<PrivateID>ronmcleod@provider1.test</PrivateID>
<ServiceProfile>
<PublicIdentity>
<BarringIndication>0</BarringIndication>
<Identity>sip:ronmcleod@provider1.test</Identity>
</PublicIdentity>
<InitialFilterCriteria>
<Priority>0</Priority>
<ApplicationServer>
<ServerName>sip:defaultapp@tas.core.ims1.test</ServerName>
<DefaultHandling>0</DefaultHandling>
</ApplicationServer>
</InitialFilterCriteria>
</ServiceProfile>
</IMSSubscription>