Chapter 20
The Presence Service in the IMS
Chapter 19 gave an overview of the presence service on the Internet, as defined by the IETF. This chapter focuses on the use of the presence service in the IMS. We explore the IMS architecture that supports the presence service and the applicability of presence to the IMS.
3GPP has defined, in 3GPP TS 24.141 [51], a presence service that runs over IMS, but mostly, 3GPP is just maintaining the specification, not actively progressing it. The presence service in IMS has since moved to OMA. OMA considers the presence service as an enabler, i.e., the set of specifications that enables a service. The main specification of the OMA Presence SIMPLE enabler is the OMA Presence SIMPLE specification [246]. This chapter describes this OMA Presence SIMPLE enabler.
20.1 The Foundation of Services
When we described the presence service on the Internet we unveiled a few of the powerful and rich possibilities that the presence service can offer to both end-users and other services.
On the one hand, end-users benefit from the presence service since they decide what information related to presence they want to provide to a list of authorized watchers. Presentities can decide the information they want to publish, such as communication address, capabilities of the terminals, or availability to establish a communication. Watchers receive that information in real time and decide how and when to interact with the presentity. All of these features enrich the end-user ...
