22.3403GPPIP Multimedia Subsystem (IMS) messagingStage 1TS
Messaging can be divided to two different main classes based on the expectation of the sender. The sender either expects the message to be delivered immediately or he does not care so much whether the message is delivered immediately or later.
The immediate case can be further divided to two different sub-classes based on the actions required form the user before he can engage in a communication. The user can both send and receive messages without any prior actions or he may be required to join to a messaging session before the message exchange can take place.
The messaging types considered in this specification are
– Immediate messaging:
Typically, sender is aware of the availability of the recipient(s) (possibly through the use of the Presence service) before sending this type of message as, if the recipient is not available, the message may be discarded or deferred. An immediate message may be deferred by the recipient’s network based on the message filtering settings defined by the recipient or by the recipient’s IMS service provider.
– Session based messaging:
The sender and recipient expect near real time message delivery. Typically, recipients of the session based messaging that are not joined to a group or are not available will not receive the messages. Typically, a sender may send a message to all participants in the messaging session without addressing them individually.