The SIP server has no way to tell the device is no longer available until the next time the device registers (or the server tries to send a call to the device).
ASTERISK has the qualify feature, which uses a SIP OPTIONS packet to probe the peer every min or so. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of eherr Sent: Monday, November 14, 2011 5:19 PM To: 'Asterisk Users Mailing List - Non-Commercial Discussion' Subject: Re: [asterisk-users] How do extensions "stay registered" I think the question is more along the lines of how does asterisk know immediately when a sip phone becomes on line and when you unplug the phone from the network, how does asterisk essentially know immediately that it status is "UNKNOWN" If I am not mistaken. --E From: [email protected] [mailto:[email protected]] On Behalf Of Danny Nicholas Sent: Monday, November 14, 2011 5:01 PM To: 'Asterisk Users Mailing List - Non-Commercial Discussion' Subject: Re: [asterisk-users] How do extensions "stay registered" "Extensions" do not register - peers do. A peer can register itself or be registered by Asterisk. In most cases the "extension" is equivalent to the "peer" (301 = 301) but it can be quite different (301 = sipuser1) or (301 = [email protected]). From: [email protected] [mailto:[email protected]] On Behalf Of Douglas Mortensen Sent: Monday, November 14, 2011 3:52 PM To: '[email protected]' Subject: [asterisk-users] How do extensions "stay registered" I know this is probably a very basic question for many on this list. But in troubleshooting an issue, I wanted to take a step back & ask the question. In Asterisk (or maybe all SIP), how do extensions stay registered with the SIP server? Do the extensions simply register repeatedly as a means of telling asterisk "I'm still here", or are there actual keepalive packets that are transmitted to actually keep a TCP session alive? My guess is the former. But am I oversimplifying it? Is there more to the process? Thanks, - Doug Mortensen Network Consultant Impala Networks Inc CCNA, MCSA, Security+, A+ Linux+, Network+, Server+ . www.impalanetworks.com P: (505) 327-7300 F: (505) 327-7545 . -- _____________________________________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
