Method and network entities for enabling server allocation in an IMS-based Multimedia over IP network. The method includes receiving by a S-CSCF server of the network subscriber registration data, transmitting, by the S-CSCF server, information representative of subscriber data to a P-CSCF server and/or to an HSS for storing the information representative of the subscriber data in a memory by the P-CSCF server and/or by the HSS, and transmitting, by the S-CSCF server, a S-CSCF group address to the P-CSCF server and/or to the HSS, respectively, said S-CSCF group address being representative of a group of S-CSCF servers, the S-CSCF server being included in said group of S-CSCF servers.