The IMS: IP Multimedia Concepts And Services, Second Edition

4.11. Example signalling flows of presence service operation

4.11.1. Successful subscription to presence

Figure 4.3 shows an example flow of a watcher who has successfully subscribed to the presence information of a presentity residing in a different network while the watcher resides in her home network. The flow shows an initial NOTIFY request to the SUBSCRIBE request.

4.11.2. Successful publication of presence information

Figure 4.4 shows an example flow of a presentity that has successfully published presence information. In this scenario the User Equipment (UE) is behaving as a PUA. This typically results in the Packet-Switched (PS) domain generating notifications to watchers.

Figure 4.3. Successful subscription to presence.

Figure 4.4. Successful publication.

4.11.3. Subscribing to a resource list

Figure 4.5 shows an example flow of a watcher who is subscribing to the presence information of a resource list that was created earlier (possibly using XCAP). The list of presentities (resources) is referenced using a SIP URI. The flow shows the immediate NOTIFY request that is sent after receiving the SUBSCRIBE request. If the Resource List Server (RLS) does not hold any presence information about the resources in the list, then the NOTIFY request may carry an empty body. ...