On 5/06/2011 1:31 PM, Eugen Dedu wrote:
Hi,
ekiga.net registrar uses kamailio 1.5.3 (yes, a bit old...) and for users who are not registered an empty NOTIFY body is returned when asked by a SUBSCRIBE. What does this mean from SIP standard point of view, and from kamailio point of view (are they identical?) I see in RFC3265/3.1.6.2: .... If the resource has no meaningful state at the time that the SUBSCRIBE message is processed, this NOTIFY message MAY contain an empty or neutral body but is difficult for me to interpret what it means.
Example: I ask the presence for a user xyz who registered and quit application long time ago:
..deleted
To resume: What does SIP standard say about this NOTIFY with empty body? Does this mean that the user xyz is offline?
Or does this mean that user's status has not changed? In fact, the NOTIFY with empty body (as shown above) is the first one sent by kamailio, so there is no "previous" state of that user, hence "unchanged" status has no meaning.
Here is my understanding.
If the NOTIFY is the first NOTIFY sent in response to the SUBSCRIBE, then the NOTIFY should be ignored. Opal should be doing this.
if the NOTIFY is *not* the first NOTIFY, i.e. there was a previous NOTIFY that contains a valid presence status, then the previous status should be used.
Craig