Hello,

thanks, I found that as well, but I didn't wanted to believe is no update to it in regard to sip client behavior. A phone replying with such generic code is really misleading for such case . So I searched further in 4xx class, base rfc and other extensions, and could not find anything.

Cheers, Danie

On 4/24/12 2:17 PM, Andrew Pogrebennyk wrote:

Hi Daniel, See RFC 3261 section 12.2.2:

If the remote sequence number was not empty, but the sequence number
of the request is lower than the remote sequence number, the request
is out of order and MUST be rejected with a 500 (Server Internal
Error) response.

However, 400 or some 4xx response would seem more reasonable to me, to let the UAC know it just did something wrong. And I'm not the only one: http://comments.gmane.org/gmane.ietf.sip-implementors/8970

On 04/24/2012 02:10 PM, Daniel-Constantin Mierla wrote:

...

Hello,

I was wondering if someone here can point quickly where specs mention what is the right reply code to send when a request within dialog is received with lower cseq value than the previous request. I couldn't spot the part in the RFC yet, if any related exists.

Cheers, Daniel

Hello,

On 4/24/12 3:55 PM, Olle E. Johansson wrote:

24 apr 2012 kl. 14:27 skrev Daniel-Constantin Mierla:

...

Hello,

thanks, I found that as well, but I didn't wanted to believe is no update to it in regard to sip client behavior. A phone replying with such generic code is really misleading for such case . So I searched further in 4xx class, base rfc and other extensions, and could not find anything.

You propably want to add a reason header or something to explain for the poor guy running wireshark. The error code is not all.

I would do if I was developing the hard/softphone. So I was actually wondering how to detect such situation based on the reply received in the proxy.

Btw, what Asterisk/Sems does in this situation (just for the developers of such end points here :-) ), any special hint-header added?

Cheers, Daniel

/O

...

Cheers, Danie

On 4/24/12 2:17 PM, Andrew Pogrebennyk wrote:

...

Hi Daniel, See RFC 3261 section 12.2.2:

If the remote sequence number was not empty, but the sequence number
of the request is lower than the remote sequence number, the request
is out of order and MUST be rejected with a 500 (Server Internal
Error) response.

However, 400 or some 4xx response would seem more reasonable to me, to let the UAC know it just did something wrong. And I'm not the only one: http://comments.gmane.org/gmane.ietf.sip-implementors/8970

On 04/24/2012 02:10 PM, Daniel-Constantin Mierla wrote:

...

Hello,

I was wondering if someone here can point quickly where specs mention what is the right reply code to send when a request within dialog is received with lower cseq value than the previous request. I couldn't spot the part in the RFC yet, if any related exists.

Cheers, Daniel

-- Daniel-Constantin Mierla - http://www.asipto.com http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda

---

SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users

---

• Olle E Johansson - oej@edvina.net
• Cell phone +46 70 593 68 51, Office +46 8 96 40 20, Sweden

o Daniel-Constantin Mierla on 04/24/2012 04:04 PM:

Btw, what Asterisk/Sems does in this situation (just for the developers of such end points here :-) ), any special hint-header added?

SEMS adds "Retry-After: 0" if the method is NOTIFY. Additionally, you can now ignore the low CSeq for NOTIFY if ignore_notify_lower_cseq=yes in sems.conf.

but yes, a Warning would be in order.

Stefan