8 Addressing requirements
22.3403GPPIP Multimedia Subsystem (IMS) messagingStage 1TS
It shall be possible to use a single address to identify the recipient. The single address shall be either a SIP URL, a network address identifier (NAI as defined in RFC2486 [3]) or a MSISDN.
IMS Messaging shall be based on existing IMS address resolution and routing mechanisms.