Hi all. I have an issue/doubt regarding Via header. The scenario is a FreeSwitch connected to a Mavenir's IMS; call is generated by FS towards Mavenir's IMS (it is ok) and release (BYE) is coming from IMS: Request-Line: BYE sip:gw+ibcf_gateway@192.168.242.42:5060;transport=udp;gw=ibcf_gateway SIP/2.0 Message Header [truncated]Via: SIP/2.0/UDP scscf.ims.mnc001.mcc001.3gppnetwork.org:5060;rport;branch=z9hG4bKmavodi-0-4c-bf-2-640020-4df45e927c208f36,SIP/2.0/UDP tas.ims.mnc001.mcc001.3gppnetwork.org:5060;received=192.168.239.37;rport=5060;branch=z9hG4bK Transport: UDP Sent-by Address: scscf.ims.mnc001.mcc001.3gppnetwork.org Sent-by port: 5060 RPort: rport Branch: z9hG4bKmavodi-0-4c-bf-2-640020-4df45e927c208f36 Transport: UDP Sent-by Address: tas.ims.mnc001.mcc001.3gppnetwork.org Sent-by port: 5060 Received: 192.168.239.37 RPort: 5060 Branch: z9hG4bKmavodi-0-7e-76-1-ffffffff-3029420078-24076 Max-Forwards: 69 From: <sip:+628811451570@ims.mnc001.mcc001.3gppnetwork.org>;tag=mavodi-0-7e-76-1-ffffffff-_000C2939994E-5e0c-a2ac4700-5df-5ae2f6d8-24075 To: "+628811452131" <sip:+628811452131@192.168.242.42>;tag=HHXppypZBv2aS Call-ID: f4973e3c-c4a8-1236-15b0-000c29581a5f CSeq: 122076474 BYE Content-Length: 0 P-Access-Network-Info: 3GPP-E-UTRAN-TDD;utran-cell-id-3gpp=5102800640033101 P-Charging-Vector: icid-value=0.82.760-1524823768.21;icid-generated-at=192.168.239.35;term-ioi=Ioi1;orig-ioi=22345 P-Charging-Function-Addresses: ccf=ims.mnc001.mcc001.3gppnetwork.org;ecf=ims.mnc001.mcc001.3gppnetwork.org;ccf=ims.mnc001.mcc001.3gppnetwork.org;ecf=ims.mnc001.mcc001.3gppnetwork.org Status-Line: SIP/2.0 200 OK Message Header Via: SIP/2.0/UDP scscf.ims.mnc001.mcc001.3gppnetwork.org:5060;rport=5060;branch=z9hG4bKmavodi-0-4c-bf-2-640020-4df45e927c208f36;received=192.168.239.36 Transport: UDP Sent-by Address: scscf.ims.mnc001.mcc001.3gppnetwork.org Sent-by port: 5060 RPort: 5060 Branch: z9hG4bKmavodi-0-4c-bf-2-640020-4df45e927c208f36 Received: 192.168.239.36 From: <sip:+628811451570@ims.mnc001.mcc001.3gppnetwork.org>;tag=mavodi-0-7e-76-1-ffffffff-_000C2939994E-5e0c-a2ac4700-5df-5ae2f6d8-24075 To: "+628811452131" <sip:+628811452131@192.168.242.42>;tag=HHXppypZBv2aS Call-ID: f4973e3c-c4a8-1236-15b0-000c29581a5f CSeq: 122076474 BYE User-Agent: FreeSwitch Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, REGISTER, REFER, NOTIFY Supported: timer, path, replaces Content-Length: 0 In the 200 OK replied back by FS to the BYE message, part of the 'Via' header is "missing". According to RFC 3261: "The Via header field values in the response MUST equal the Via header field values in the request and MUST maintain the same ordering". Is it a expected behavior? Any variable to set in order to get the "original" 'Via' header in the answer? Br. Stefano