Disconnect during fax transmission

[rcraig114]

I am trying to fax over my SIP Trunk and for whatever reason, the call disconnects as soon as the two fax machines start to transmit. I can receive faxes all day long, but outgoing fails. Using a FXS card on Cisco 1760 which sends everything to SIP Trunk provider. Any help is appreciated.

 

[whykap]

Where are the sip trunks terminating? On the 1760 as well?
What are the sip debugs showing? It's interesting that the issue is only with outgoing? Are all outgoing faxes failing or a specific number you are trying?

 

[rcraig114]

I'm running CME on the 1760, which terminates the SIP trunk as well. I've confirmed with my provider that they are running pass-thru for faxes, which is exactly how I have my incoming and outgoing dial-peers configured. I've tried to mess with debugging the traffic/connections, but unfortunately I don't know what I'm looking at. It really doesn't make any sense. If it was my configuration or hardware, wouldn't the incoming faxes fail as well? Oh, and it fails to several known good numbers.

 

[whykap]

You would think it would fail both ways, but it is not necessarilly always the case.
Do all outgoing faxes fail then or is it intermittent?
What is your wan connection and speed up and down?
Are you running the latest or at least one of the latest IOS releases? Whats your IOS version and CME version?

 

[rcraig114]

It seems to be intermittent. I can't confirm with my provider right now if anything has changed on their end, but as of right now, I would assume everything is fine. My WAN is a cable connection with 25mb/5mb. I consistently get more speed than that, but thats what my plan is rated for. Running the below which as far as I know, is the latest for a 1760.

Cisco IOS Software, C1700 Software (C1700-IPVOICEK9-M), Version 12.4(15)T7


CONFIG (Version=4.1(0))
=====================
Version 4.1(0)

 

[whykap]

If I had to take a guess you have a qos issue. You don't have incoming issues because your download speed is 25mg but going out your upload is less. Do you have any qos configured and is your cable provider honoring it? Meaning do you have a qos SLA with them?
You are running older IOS and CME but this is a discontunued router, not much you can do about it. I don't think that is your issue anyway. I think the issue is with qos as mentioned already.

 

[rcraig114]

I want to say QOS, but what is weird is the fax machine is sitting right next to me when I am trying to send. I literally hear a sound like a disconnect when the distant end first picks up, and then another click (almost like someone is picking up the phone or something) when they start transmitting. Obviously the second click kills the conversation and the fax machine eventually ends the call.

 

[rcraig114]

You know, I may have an even bigger problem. I managed to get debugging to work. I did a debug ccsip error and the below is what I got. Keep in mind that the first and last errors came across the terminal while the fax machine was inactive. Everything else is during the fax transmission.


Oct 2 20:51:27.031: //-1/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/SIP/Error/rtpAvpCodec_to_voipCodec: Unexpected RTP PayloadType :255 in SDP Body
core_router#
Oct 2 20:52:10.739: //10635/30A8D199-EC6F-11E0-993F-D226201F8136/SIP/Error/sipSPIProcessCallInfoHeader: Call-Info header with for Unsolicited Notify Absent,Disabling Unsolicited Notifies
Oct 2 20:52:11.444: //10636/00000000-0000-0000-0000-000000000000/SIP/Error/ccsip_api_register_result_ind: Message Code Class 4xx Method Code 100 received for REGISTER
Oct 2 20:52:11.580: //10637/00000000-0000-0000-0000-000000000000/SIP/Error/ccsip_api_register_result_ind: Message Code Class 4xx Method Code 100 received for REGISTER
Oct 2 20:52:15.483: tdiff:86463443 tx2:236 rx2:238 pps2:50 ve:0 exp_p2:13820 pmc:1

Oct 2 20:52:15.483: Potential Mute Call:
Oct 2 20:52:15.483: CallID1=10634; CallID2=10635; ConfID=33
Oct 2 20:52:15.483: Leg 1: CallID=10634; TX packets: 237; RX packets: 236
Oct 2 20:52:15.483: Leg 2: CallID=10635; TX packets: 236; RX packets: 238
core_router#
Oct 2 20:53:27.028: //-1/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/SIP/Error/rtpAvpCodec_to_voipCodec: Unexpected RTP PayloadType :255 in SDP Body

 

[whykap]

what does the
show sip register ua-status
command show?
All the 1xx messages are informational no other errors?
What debug are you running?

 

[whykap]

sorry the command is
show sip-ua register status

 

[rcraig114]

core_router#show sip-ua register status
Line peer expires(sec) registered
============ ============= ============ ===========
116301 -1 38 yes
5208430759 16 49 no
core_router#

116301 is the account number I use to register in sip-ua, 5208430759 is one of the DID's assigned to my account. I'm not sure why it is even appearing in the status.

 

[Silverblade]

I had also the problem of premature disconnecting on a CallManager 6.0, but with a vg224 I fixed the problem as following.

I the CallManager I set the VG224 on Fax passthrough and modem passthrough, on the vg224 ports I did put the following config.

voice service voip
fax protocol pass-through g711ulaw
modem passthrough nse codec g711ulaw
sip


Also on the fax machine it self I did set the RX and TX speeds to 9600 and turned ECM off.

After these setting i had no problem at all.

(I did also test with a ATA186, but here it all worked the first time (with adding the speed and ECM settings to the fax)).

 

[rcraig114]

I spent most of last night trying those commands both at a global level and on the individual dial-peers. I even tried fax rate disable. Still, no effect. I am starting to think I have a flaky router or something. I'm at a loss.

 

[whykap]

when was the last reboot of the router? You might give that a shot.

 

[rcraig114]

I did that almost every time I made a change, just to rule out some old code still stuck in the system. For whatever reason I had one successful outgoing last night. Of course when I tried again, it failed. There was no rhyme or reason for the success either. The same settings that were successful are failing.