Hi Sarvpriya,
Thanks for your quick responding
So when it understand it right,
- The UAS MAY send the 180 ringing with require header since the
Rseq is incremented by 1 and the first reliable provisional response has been
acknowledged.
- The UAC MUST respond with an PRACK.
Best regards,
Peter Nijhuis
Technisch Consultant
Televersal Group
Bezoekadres: Nedervonder 19, 5061 JP, Oisterwijk
Postadres: Postbus 37, 5066 ZG, Moergestel
T: +31 13 523 11 89 | F: +31 13 523 11 88
I: www.televersalgroup.com | E: [email protected]
=============================================================================================================
Van: $...@r\/|>r!`/@ [mailto:[email protected]]
Verzonden: woensdag 21 juli 2010 10:42
Aan: Peter Nijhuis
CC: [email protected]
Onderwerp: Re: [Sip-implementors] retransmission of 180Ringing with require:
100rel
Hi Peter,
RFC 3262 for UAS section 3 clearly says
"After the first reliable provisional response for a request has been
acknowledged, the UAS MAY send additional reliable provisional responses. The
UAS MUST NOT send a second reliable provisional response until the first is
acknowledged. After the first, it is RECOMMENDED that the UAS not send an
additional reliable provisional response until the previous is acknowledged.
The first reliable provisional response receives special treatment because it
conveys the initial sequence number. If additional reliable provisional
responses were sent before the first was acknowledged, the UAS could not be
certain these were received in order."
For UAC behavior section 4 says
" Handling of subsequent reliable provisional responses for the same initial
request follows the same rules as above, with the following difference:
reliable provisional responses are guaranteed to be in order. As a result, if
the UAC receives another reliable provisional response to the same request, and
its RSeq value is not one higher than the value of the sequence number, that
response MUST NOT be acknowledged with a PRACK, and MUST NOT be processed
further by the UAC. An implementation MAY discard the response, or MAY cache
the response in the hopes of receiving the missing responses.The UAC MAY
acknowledge reliable provisional responses received after the final response or
MAY discard them."
But for sure it increases the traffic.
On Wed, Jul 21, 2010 at 1:20 PM, Peter Nijhuis
<[email protected]> wrote:
Hello All,
I'm facing the following problem:
An incoming call is first ringing on a call center queue:
The UAS is sending a 180 Ringing with SDP and a require: 100rel, the UAC
responds with a PRACK and the UAS again with an 200 OK.
Then the call is actually ringing on a UA (IP hardphone)
The UAS send a 180 Ringing again with an SDP and a require:100rel, but
the UAC ignores this as is seems a duplicate message.
<--
INVITE/SDP supported: 100rel
100 Trying -->
180 Ringing/SDP -->
Require: 100rel RSeq:1
<-- PRACK
200 OK -->
180 Ringing/SDP -->
Require: 100rel RSeq:2
180 Ringing/SDP -->
Require: 100rel RSeq:2
180 Ringing/SDP -->
Require: 100rel RSeq:2
180 Ringing/SDP -->
Require: 100rel RSeq:2
180 Ringing/SDP -->
Require: 100rel RSeq:2
Is the UAS allowed to send multiple 180 Ringing with a require header
field?
Best Regards,
Peter Nijhuis
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--
cheers!!!!
sarvpriya
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