This TS specifies a client for the Multimedia Telephony Service for IMS (MTSI) supporting conversational speech (including DTMF), video and text transported over RTP with the scope to deliver a user experience equivalent to or better than that of Circuit Switched (CS) conversational services using the same amount of network resources. It defines media handling (e.g. signalling, transport, jitter buffer management, packet-loss handling, adaptation), as well as interactivity (e.g. adding or dropping media during a call). The focus is to ensure a reliable and interoperable service with a predictable media quality, while allowing for flexibility in the service offerings.
The scope includes maintaining backward compatibility in order to ensure seamless inter-working with existing services available in the CS domain, such as CS speech and video telephony, as well as with terminals of earlier 3GPP releases. In addition, inter-working with traditional PSTN and emerging TISPAN network is covered.
The specification is written in a forward-compatible way in order to allow additions of media components and functionality in releases after Release 7.
MTSI clients can support more than conversational speech, video and text, which is the scope of this TS. See TS 22.173 for the definition of the Multimedia Telephony Service for IMS.
TS 26.235 and TS 26.236 do not include the specification of an MTSI client, although they include conversational multimedia applications. Only those parts of TS 26.235 and TS 26.236 that are specifically referenced by this TS apply to Multimedia Telephony Service for IMS.