As multimedia messaging services (MMS) begins to take off, the big issue in becoming a success is more than just phone-to-phone interoperability - it depends on verification between multi-tier clients to multi-tier delivery platforms. As network capacity and device capabilities increase, various companies are planning the introduction of other media types such as video messages based on MMS. On the longer-term messaging road-map, as mobile telecoms move towards the third-generation 'all Internet protocol (IP)' architecture, the 3GPP has identified a possible extension of mobile messaging functionality based on the IP multimedia subsystem (IMS) and session initiation protocol (SIP). One of the attractive characteristics of SIP is the ability to create real-time sessions between groups of users, which has obvious advantages in the construction and extension of messaging services.