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support for RFC 3326

Unanswered Question
Apr 27th, 2011
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Hi Experts, we use Cisco SPA IP phone without problem. Recently we encountered an issue with CANCEL messages with REASON CAUSE.

The SPA doesn't understand this message and so, in case of no response, the call never stops.

If in the CANCEL message there isn't any REASON CAUSE the call is stopped normally.

Can SPA 30x supports RFC 3326? Can you implement this feature in the next firmware or fix misunderstanding messages?

Thanks in advance.

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Overall Rating: 4 (1 ratings)
nseto Thu, 05/05/2011 - 09:39
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Hi, please enclose a trace of this and I'll enter a cdet enhancement request for this.  Thanks.

nseto Fri, 05/06/2011 - 09:06
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I was going over the trace and it shows for the mac address src and dest, innophone.  In the trace, I couldn't find reference to the SPA phone.

And in the log file, I only see the SPA phone in the SIP Register.  Do you have a trace and log where the SPA phone and mac is shown?  I don't want to submit it without showing explicitly this info as dev may come back to me and reject due to this.  Thanks.

aemcomcco Fri, 05/06/2011 - 11:19
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In attached you can find a correct trace and syslog.
SPA303 is configured as extension 355 of an Innovaphone PBX.
When the caller 03493048400 calls the extension 355, the SPA303 rings normally. If the call is cancelled the SPA rings continuosly. To stop the ringing I must pick up the SPA headset and disconnect the call (off hook - on hook).

The difference in a working scenario is the presence of REASON CAUSEs in CANCEL messages:

Reason: SIP;cause=200;text="OK";ms-acceptedby="sip:[email protected]:5560"

In the SPA 303 messages the User-Agent name is omitted (see config screenshot).


nseto Fri, 05/06/2011 - 13:29
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Thanks, I've entered the cdet, it's CSCtq15881.  Where if the phone receives Cancel with reason/cause, it doesn't do anything.  Without the reason/cause, the phone does react to the cancel.

FYI, there's no user agent for the spa phone in the trace because the 'SIP User Agent Name' is blank in your config.  The default in there is $VERSION, so I've told the dev that the mac address is that of the spa phone.  Thanks.

aemcomcco Fri, 08/12/2011 - 02:49
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Hi Nelson, I've investigated the problem.

This issue is caused by the Microsoft extension in Reason header.
If I remove the string   ms-acceptedby="sip:[email protected]:5560",    SPA phones work right.

So SPA phones correctly undestand Reason cause messages like  Reason: SIP;cause=200;text="OK" but don't understand Microsoft Session Initiation Protocol (SIP) Routing Extensions.


nseto Fri, 08/12/2011 - 08:36
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Thanks, I've updated the cdet info with your comments.

nseto Fri, 09/30/2011 - 13:40
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Notes from dev

According to Microsoft doc:

Section Handling 2XX Responses

A SIP proxy compliant with this protocol SHOULD handle 2XX responses according to proxy behavior described in [RFC3261] section 16.7. In addition, the CANCEL requests sent out as a result of a 2XX response SHOULD have an ms-acceptedby parameter in the Reason header field. The ms-acceptedby parameter value SHOULD be set to the address-of-record of the destination user agent that sent the 2XX response.

In addition, an improvement is being done on the client side to prevent server error (to be in an upcoming release)


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