Hi, I am not sure I understand the issue, but in the "old" telephony world you also have to try to call someone before you actually know if he is plugged in or not, or if someone's mobile phone is switched on or not. The basic SIP protocol itself does not provide a mechanism to inform if people are plugged in or not (in IP terms I guess we should say LOGGED in or not), and it is not even the purpose of the protocol to do that. However, you could for example implement a presence application to handle it. Regards, Christer Holmberg Ericsson Finland Barry Desborough wrote: > > The absence of any current registrations, and the absence of INVITE > responses - that's all there is within the scope of SIP as far as I know. > There are no <<here I am, I'm up>> messages specified for the phone itself. > > Maybe I don't understand your question, but you _have_ to try sending > messages to see if a SIP phone is on the net. Hopefully, all SIP phones > support PING. Some may support SNMP. > > Barry Desborough > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] > Sent: 22 May 2001 12:47 > To: Barry Desborough > Cc: [EMAIL PROTECTED] > Subject: RE: [Sip-implementors] plug/unplug SIP phone ?? > > Quoting Barry Desborough <[EMAIL PROTECTED]>: > > > If you're concerned about a SIP phone being unplugged with a call up, > > you > > can send periodic INVITEs for the current call leg and check for > > responses. > > Also, you could also check for ICMP destination/port unreachable > > messages > > for signaling and media. > > > > Barry Desborough > > OK, but we are not notified that a SIP phone is unplugged when no call is > up. > To Check ICMP messages I have to send messages. What if no messages are sent > ? > Does it mean that there no offcial mechanism to check plug/unplug state of a > SIP > phone? > > patrick > _______________________________________________ > Sip-implementors mailing list > [EMAIL PROTECTED] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
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