4.12 Network Address Translation traversal in access network

23.2283GPPIP Multimedia Subsystem (IMS)Release 18Stage 2TS

It shall be possible to support the scenario where a NAT(-PT)/NAPT(-PT) residing between the IMS functionality in the UE and the P‑CSCF has to be traversed for IMS communication. This shall include at least the types of NATs that implement address and port dependent mapping together with address and port dependent filtering, RFC 4787 [51].

NOTE: The UE may be one piece of equipment, or it may be a network of elements located on a end-user’s physical premises.