Subject: [Sipping] problem with sip resonse code mapping to isup

From: Juha Heinanen <[email-masked]>
Date: Tue, 22 Jan 2002 16:33:40 +0200

if i try to call from pstn to a sip phone that is not currently
registered, the home proxy of the phone returns "404 not found".
according to draft-ietf-sipping-isup-00.txt the sip/isup gw then maps
that to "1 Unallocated number".

i think this is plain wrong, because surely the number has been
allocated to the sip phone.  the phone just happens to be off-line.  in
finland pstn turns "1 Unallocated number" into a voice reply that goes
something like "the number doesn't exist, please check the number and
try again".  from that the called gets the wrong impression that he has
got a wrong number.

if i call to a cell phone that happens to be offline, i get from pstn a
message that goes something like "the number you tried to call is not
currently reachable, please try again later".  i believe this is
generated from "18 No user responding".

i would like to get this same announcement if i call a sip phone whose
number is not currently registered, but which the proxy knows exists in
its domain.  according to the table in draft-ietf-sipping-isup-00.txt, i
can get "18 No user responding" if the proxy would return "480
Temporarily unavailable". this however, is not possible according to
bis-05:

23.4.16 480 Temporarily Unavailable The callees end system was
contacted successfully but the callee is currently unavailable
(e.g., not logged in, logged in in such a manner as to
preclude communication with the callee or activated the do not
disturb feature).

i.e., only the phone, not the proxy, can return such a message, but
obviously in this case it can't because proxy doesn't know where the
phone is and thus can't forward the invite to it.

clearly something needs to be done in order to resolve this issue.  i'll
include also the sip list, since it would be possible to do the fix in
either document.  my initial feeling is that we would need a new error
response "4xx Offline", alternatively we need to change the wording of
404, because now 404 should be returned if the "user doesn't exist",
which to very ambiguous to me.

-- juha

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---

From: Gonzalo Camarillo <[email-masked]>
Date: Wed, 23 Jan 2002 23:03:02 +0200

Hello Juha,

> i'm wondering what has happened to the authors of
> draft-ietf-sipping-isup-00.txt, since noone has showed up to defend
> their table.  may be they are "410 gone" :-).

We are pretty busy finishing bis-06. That's why we had not answered your
mail before. Anyway, if you send the mail to the mailing list and cc us
as well you will get faster responses.

The definition of 480 Temporarily unvailable says: "This status is also
returned by a redirect server that recognizes the user identified by the
Request-URI but does not currently have a valid forwarding location for
that user."

We will change "redirect server" by "redirect or proxy server" in
bis-06. 

With this change, your example does not work because your SIP server is
returning 404 instead of 480. If it returns 480 the tables in the
mapping draft work fine.

Thanks,

Gonzalo

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