Proxy-call session control function (P-CSCF)

A system comprising:

• processor(s);
• and
• computer-readable medium storing programming instructions that, when executed by the processor(s), cause the processor(s) to:
• receive, by a unified data management function (UDM), a proxy-call session control function (P-CSCF) restoration indication over a single N70 interface extending directly between the UDM and a serving-call session control function (S-CSCF);
• transmit, by the UDM, the P-CSCF restoration indication to a session management function (SMF) responsive to receiving the P-CSCF restoration indication over the single N70 interface;
• based on at least receiving the P-CSCF restoration indication, send, from the SMF to a user equipment (UE), an internet protocol (IP) messaging system (IMS) Packet Data Network (PDN) connection release message instructing the UE to release registration with a first P-CSCF and re-register with a second P-CSCF that is different than the first P-CSCF;
• receive an indication, by an application server (AS), that the UE is registered with the second P-CSCF;
• and
• based on at least receiving a session initiation message, establish a data traffic session for the UE with the second P-CSCF.