Methods and apparatus facilitate recovery of an IMS in which an S-CSCF has suffered a restart (after a failure, software upgrade, or other reasons). One or more of first and second methods comprise submitting, from the S-CSCF towards a HSS, contact data required by the S-CSCF to contact a given subscriber, or to contact a proxy server through which the subscriber is accessible; storing the contact data at the HSS; and providing from the HSS towards an IMS entity, which may be previously assigned S-CSCF or a new S-CSCF, contact information elements selectable from the contact data.