Hey everyone! I have spent the last 14 hours trying to get this to work, but it still has failed me. I have made progress. First let me give you the background, VoIP provider Broadvoice, Firewall Cisco Pix (Setup as a 1:1 associatoin from outside to inside 100% port pass-through right now). Ext IP 68.16x.149.74, Int 192.168.2.7 I am trying to Fax over IP, and at first when setting up 3cx to recieve faxes over one of my phone lines it would drop the call instantly. i disabled the SRT which gave me some progress, i see a handshake but keeps dropping call due to no ACT recieved. here is the log output i am recieving. 12:24:09.449 [MS105000] C:5.2: No RTP packets were received:remoteAddr=18.104.22.168:10000,extAddr=0.0.0.0:0,localAddr=127.0.0.1:7008 12:24:08.902 [CM503008]: Call(5): Call is terminated 12:24:08.902 [CM503021]: Call(5): ACK is not received 12:23:36.887 [MS210003] C:5.2:Answer provided. Connection(transcoding mode[unsecure]):127.0.0.1:7008(7009) 12:23:36.887 [MS210001] C:5.1:Answer received. RTP connection[unsecure]: 22.214.171.124:19318(19319) 12:23:36.887 Remote SDP is set for legC:5.1 12:23:36.465 [MS210002] C:5.1:Offer provided. Connection(transcoding mode): 68.16x.149.74:9008(9009) 12:23:36.465 Remote SDP is set for legC:5.2 12:23:35.652 Session 3801 of leg C:5.1 is confirmed 12:23:35.512 [CM503007]: Call(5): Device joined: sip:email@example.com:5100;user=phone 12:23:35.496 [CM503007]: Call(5): Device joined: sip:firstname.lastname@example.org:5060 12:23:35.496 [MS210003] C:5.1:Answer provided. Connection(transcoding mode[unsecure]):68.16x.149.74:9008(9009) 12:23:35.496 [MS210001] C:5.2:Answer received. RTP connection[unsecure]: 68.16x.149.74:10000(10001) 12:23:35.480 Remote SDP is set for legC:5.2 12:23:35.480 [CM503002]: Call(5): Alerting sip:email@example.com:5100;user=phone 12:23:35.402 [CM503025]: Call(5): Calling @[Dev:sip:firstname.lastname@example.org:5100;user=phone] 12:23:35.402 [MS210002] C:5.2:Offer provided. Connection(transcoding mode): 127.0.0.1:7008(7009) 12:23:35.387 [CM503004]: Call(5): Route 1: @[Dev:sip:email@example.com:5100;user=phone] 12:23:35.387 [CM503010]: Making route(s) to <sip:firstname.lastname@example.org:5060;user=fax> 12:23:35.387 [MS210000] C:5.1:Offer received. RTP connection: 126.96.36.199:19318(19319) 12:23:35.387 Remote SDP is set for legC:5.1 12:23:35.387 [CM505003]: Provider:[BV-3005(FAX)] Device info: Device Not Identified: User Agent not matched; Capabilities:[reinvite, replaces, able-no-sdp, recvonly] UserAgent:  PBX contact: [sip:email@example.com:5060] 12:23:35.355 [CM503001]: Call(5): Incoming call from 301xxx2137@(Ln.10004@BV-3005(FAX)) to <sip:firstname.lastname@example.org:5060;user=fax> 12:23:35.355 [CM503012]: Inbound office hours rule (unnamed) for 10004 forwards to Fax:8888 12:23:35.355 Looking for inbound target: called=240xxx3005; caller=301xxx2137 12:23:35.340 [CM500002]: Info on incoming INVITE: INVITE sip:email@example.com:5060 SIP/2.0 Via: SIP/2.0/UDP 188.8.131.52:5060;branch=z9hG4bK-BroadWorks.192.168.0.3-192.168.32.221V5060-0-570030092-1359869359-1268155412502- Max-Forwards: 69 Contact: <sip:firstname.lastname@example.org:5060> To: "Jason"<sip:email@example.com> From: "Intelsat"<sip:firstname.lastname@example.org;user=phone>;tag=9abc Call-ID: email@example.com CSeq: 1 INVITE Supported: 100rel Content-Length: 0 It dosent seem to look like other loggs i have seen for recieving faxes.