[OpenSIPS-Users] SIP message relay order

[Stas Kobzar]

Hello List,

My call flow has initial INVITE and re-INVITE to update RTP IP/port.
Usually everything works well, but sometimes OpenSIPS come up with
following example:

UA                 OpenSIPS          PSTN GW
-------------------------------------------
INV(CSeq: 100) -----> | ---> INV(CSeq: 100)
<---- 200 OK          | <--- 200 OK

(UA sends ACK then new INVITE)

ACK(CSeq: 100) -----> |
reINV(Cseq: 101) ---> |

(OpenSIPS relays first INVITE then ACK)
                      | ---> reINV(CSeq: 101)
                      | --->   ACK(CSeq: 100)

When PSTN gateway receives re-INVITE before ACK for previous INVITE
it responds 500 with Retry-After header.
This is correct behaviour which conforms to the RFC 3261 section 14.2

My question is:
Is it possible to assure order of received and relayed messages within the
same SIP session? Is there any configuration parameter?

Thank you,
-- 

Stas Kobzar

Developeur VoIP / VoIP Developer


Modulis­.ca Inc.

# Bureau / Office: 514-284-2020 x 246

Email: s <http://firstname.lastname>tas.kobzar at modulis.ca

https://www.modulis.com
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