Yes. The REGISTER method is meant to indicate the presence of users, not
phones, but if there are no current registrations associated with a SIP
phone, there's nobody to call even if the phone _is_ on the net.
Barry Desborough
-----Original Message-----
From: Bob Penfield [mailto:[EMAIL PROTECTED]]
Sent: 22 May 2001 14:08
To: Barry Desborough; [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]
Subject: Re: [Sip-implementors] plug/unplug SIP phone ??
Actually, the REGISTER message can be viewed as a SIP phone's "here I am,
I'm up" depending on the expiration time in the registration. If the SIP
phones re-registration interval is relatively short (on the order of a few
minutes) the outbound proxy knows that it is there. If the proxy does not
receive another REGISTER when the registration expires, it could consider
the phone down and stop sending it INVITEs.
(-:bob
Robert F. Penfield
Chief Software Architect
Acme Packet, Inc.
130 New Boston Street
Woburn, MA 01801
[EMAIL PROTECTED]
----- Original Message -----
From: "Barry Desborough" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Sent: Tuesday, May 22, 2001 8:10 AM
Subject: RE: [Sip-implementors] plug/unplug SIP phone ??
> 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
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> [EMAIL PROTECTED]
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>
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