Motivation:

You arrive at a foreign city. You feel lonely, tired and confused. Wouldn’t it feel warmer a bit if you were personally welcomed by the hosting city upon arrival…? Not to mention learning about the local weather and traffic situation.

The feature:

SIP Application Server can subscribe to a Presence Server, in order to receive automatic presence notification when the user has arrived at to a certain place and his/her device is turned ON.
 

Then upon arrival at the particular location (e.g. landing in Chicago) the Application Server will get notified for the event by the Presence server. It can then send the user welcome notification + potentially local news, local weather etc.
 

The first part of the procedure (the presence notification) may be alternatively accomplished by means of third party registration (triggered by user’s profile) as shown in the slide below.

How this can be accomplished:

Figure 1 below illustrates how this can be accomplished.