I was making some fax tests using a Cisco AS5300, OpenSER 1.0.1 and a Grandstream HandyTone 486. Everything results fine when I previously make the same test directly from the HandyTone to the AS5300, however when I put OpenSER in the middle the fax connection could not be established. Checking captures at both ends, I noticed the HandyTone was not receiving the OK response to its RE-INVITE request, but the AS5300 was sending it. Looking a capture in the OpenSER, I suppose it didn’t send the OK response from the AS5300 to the HandyTone because the format of the Via Header used by the AS5300. Look at the captures below, the AS5300 sends the Via header in a comma-separated format instead using a line for each one. Is there a way to workaround this?

I think my best option is to modify the OpenSER code to support both formats. Is this something that somebody already does it? If the answer it is not, where can I start?

I’ll appreciate any help.

Dioris Moreno

Cisco AS5300 IP Address: AAA.BBB.CCC.DDD

OpenSER IP Address: WWW.XXX.YYY.ZZZ

Grandstream HT486 IP Address: FFF.GGG.HHH.III

Calling Party Number (PSTN): UserA

Called Party Number (VoIP): UserB

Message From OpenSER to Cisco AS5300

Session Initiation Protocol

Request-Line: INVITE sip:UserA@AAA.BBB.CCC.DDD:5060 SIP/2.0

Method: INVITE

Resent Packet: False

Message Header

Record-Route: <sip:WWW.XXX.YYY.ZZZ;ftag=266f5f157860b9ca;lr=on>

Via: SIP/2.0/UDP WWW.XXX.YYY.ZZZ;branch=z9hG4bK6a82.677fb8e1.0

Via: SIP/2.0/UDP FFF.GGG.HHH.III:50841;branch=z9hG4bK90436408698e6881

From: <sip:UserB@WWW.XXX.YYY.ZZZ>;tag=266f5f157860b9ca

SIP from address: sip:UserB@WWW.XXX.YYY.ZZZ

SIP tag: 266f5f157860b9ca

To: <sip:UserA@AAA.BBB.CCC.DDD>;tag=D33F86B0-94F

SIP to address: sip:UserA@AAA.BBB.CCC.DDD

SIP tag: D33F86B0-94F

Message From Cisco AS5300 to OpenSER