====== setSIPSubscribe() ======
wrtc.setSIPSubscribe() is used to subscribe to someones SIP presence status.

===== Arguments =====
wrtc.setSIPSubscribe(address,expires)
  * address - SIP address to monitor for presence status changes
  * expires - (optional) timeout in seconds after which subscription must be renewed

If no expires argument is specified timeout is set to 5 minutes.

You do not need to call wrtc.setSIPSubscribe() again after the timeout - all subsequent refreshes are taken care of by wrtc_kit. Therefore you do not need to specify any expires argument unless the SIP server used refuse to use the default 5 minute expire time.

===== Returns =====
Nothing.

===== Events =====
Event [[ixnx:wrtc:js:api:wrtc:onsippresence|wrtc.onSIPPresence()]] will occur each time monitored user's SIP presence status changes.

===== Example =====
wrtc.setSIPSubscribe("adam@foo.com") will monitor Adam's SIP presence status and calls event function [[ixnx:wrtc:js:api:wrtc:onsippresence|wrtc.onSIPPresence()]] each time his online status changes.

===== List of subscribers =====
To receive a list of all persons subscribing to your online status call wrtc.setSIPSubscribe() with your own SIP address as argument. It will trigger a special [[ixnx:wrtc:js:api:wrtc:onsippresence#subscribers|wrtc.onSIPPresence()]] event function call containing the list.