Cisco VG202 Fax with CME

a3b2c1r46 · ‎10-17-2018

I have a VG202 configured with SCCP with CME 8.6.

I cannot get fax to work reliably. The fax call comes in and my fax machine answers. The call terminates after a period of time. Typically less than 2 minutes but often less than one minute.

I have both units setup for modem pass-through but I have tried fax relay with both t38 and cisco.

I found that my PRI had SLIP errors due to a clock setting issue. I corrected that problem but the fax issue still hasn't gone away.

How can I determine what is causing the calls to drop?

Sreekanth Narayanan · ‎10-19-2018

Here's how we usually approach fax issues:
1. Check if the voice call completes -- This has happened in your case
2. Check if the switchover/escalation to fax occurs from the voice call
3. Check the quality of the stream
4. Check the fax signals themselves to see if there is a negotiation failure

Since you have got rid of the PRI slips, it will not be the source of the failure.
The next thing to check here is to see if the voice call is even escalating to the fax protocol you configured on the VG202.
For the SCCP protocol, Cisco supports the T38 nse and modem passthrough nse protocols.
Here are the required configuration on the CME as well as the VG202.

Modem passthrough nse:

voice service voip
modem passthrough nse codec g711ulaw
fax protocol none

T38 nse:

voice service voip
fax protocol t38 nse ls-redundancy 0 hs-redundancy 0

Make sure the config is applied to both of the routers. After this, make the test call and run the "show call active voice brief" output on both the routers to check if the call escalated from voice to t38/modem passthrough.
You can also run the debug voip rtp session named-events and debug fax relay t38 (if you configure t38) to check if the nse events are generated when the fax tones come in on the PRI line as well as the fxs port on the VG.

a3b2c1r46 · ‎10-19-2018

That is very good information. Thank you. I did as you suggested and configured both as modem pass-through.

I'm not totally sure the elevation to modem is happening on the CME router here is the out put of the show call active voice:

CME:

110F : 130416 10:14:00.797 DST Fri Oct 19 2018.1 +880 pid:100 Answer 2564538045
active dur 00:00:15 tx:782/130440 rx:781/124024 Tele 0/3/0:23 (130416) [0/3/0.3] tx:13320/13320/0ms g711ulaw noise:-69 acom:29 i/0:-61/-11 dBm

110F : 130417 10:14:00.801 DST Fri Oct 19 2018.2 +870 pid:20052 Originate 34 active
dur 00:00:15 tx:0/0 rx:0/0 Tele 50/0/52 (130417) [50/0/52.0] tx:0/0/0ms g711ulaw noise:0 acom:0 i/0:0/0 dBm

VG202:

Total call-legs: 2
0 : 154 236503450ms.1 +860 pid:0 Originate active dur 00:00:10 tx:531/84024 rx:530/88104 Tele 0/0 (154) [0/0] tx:8320/8320/0ms g711ulaw noise:-53 acom:6 i/0:-11/-64 dBm
0 : 155 236504330ms.1 +0 pid:0 Originate connecting
dur 00:00:10 tx:531/84024 rx:530/83864 IP 172.16.20.1:2000 SRTP: off rtt:0ms pl:6110/0ms lost:0/0/0 delay:65/65/65ms g711ulaw TextRelay: off media inactive detected:n media contrl rcvd:n/a timestamp:n/a
long duration call detected:n long duration call duration:n/a timestamp:n/a MODEMPASS nse buf:0/0 loss 0% 0/0 last 6110s dur:0/0s

Based on this information it appears as though the call leg closest to the fax machine is in modempass mode but the other call legs are in TEL mode. Am I reading that correctly?

Sreekanth Narayanan · ‎10-22-2018

You will not be able to observe any events on this debug voip rtp if the CME router is a G3 router (4000 series). The TEL legs will not show a codec change to MODEMPASS. This is because modem passthrough is a VOIP protocol. TEL legs will continue to show TEL.

Will it be possible for you to take a pcm or packet capture for a test call with the debugs? It would be good to see what's going on in the fax signaling. Also please disable the SG3 fax option in the fax machine if possible and try a call as well.

a3b2c1r46 · ‎10-23-2018

I've completed a packet capture at this link.

https://www.dropbox.com/sh/hrrsxqjdzwd5l8z/AAACzK0x1U-K3LnbzGj6pRQla?dl=0

I'm unable to discern any details from them other than that the call took place. None of the fax calls listed in these caps were sucessful. They all either terminated before any fax printout was generated or before an entire first page was generated. The only printed fax from the three separate calls was about the top inch of a cover page.

a3b2c1r46 · ‎10-26-2018

Here is the show inventory:

NAME: "3825 chassis", DESCR: "3825 chassis"

PID: CISCO3825 , VID: V05

NAME: "2nd generation four port FXO voice interface daughtercard on Slot 0 SubSlot 0", DESCR: "2nd generation four port FXO voice interface daughtercard"

PID: VIC2-4FXO , VID: V03

NAME: "2nd generation four port FXO voice interface daughtercard on Slot 0 SubSlot 1", DESCR: "2nd generation four port FXO voice interface daughtercard"
PID: VIC2-4FXO= , VID: VNAME: "Two port T1 voice interface daughtercard on Slot 0 SubSlot 3", DESCR: "Two port T1 voice interface daughtercard"
PID: VWIC-2MFT-T1 , VID: V02

NAME: "PVDMII DSP SIMM with four DSPs on Slot 0 SubSlot 4", DESCR: "PVDMII DSP SIMM with four DSPs" PID: PVDM2-64 , VID: V01

NAME: "AIM Service Engine 1", DESCR: "AIM Service Engine"
PID: AIM-CUE , VID: V02

My CME is running Cisco IOS Software, 3800 Software (C3825-ADVENTERPRISEK9-M), Version 15.1(4)M3

My VG202 is running Cisco IOS Software, VG20X Software (VG20X-IPVOICE-M), Version 12.4(22)T5

I wanted to try to upgrade the IOS on the VG but cannot as it is protected download on the website.

a3b2c1r46 · ‎10-19-2018

Also here is the output of the debug named events

*Mar 3 18:51:55.379: s=DSP d=VoIP payload 0x64 ssrc 0x1D7C sequence 0x924 timestamp 0x5A6A1EAB
*Mar 3 18:51:55.383: Pt:100 Evt:192 Pkt:00 00 00 <Snd>>>

*Mar 3 18:51:55.391: s=DSP d=VoIP payload 0x64 ssrc 0x1D7C sequence 0x926 timestamp 0x5A6A1EAB

*Mar 3 18:51:55.391: Pt:100 Evt:192 Pkt:00 00 00 <Snd>>>
*Mar 3 18:51:55.399: s=VoIP d=DSP payload 0x64 ssrc 0x1992 sequence 0x18C4 timestamp 0xE6CF45AC
*Mar 3 18:51:55.399: <<<Rcv> Pt:100 Evt:192 Pkt:00 00 00
*Mar 3 18:51:55.407: s=VoIP d=DSP payload 0x64 ssrc 0x1992 sequence 0x18C6 timestamp 0xE6CF45AC
*Mar 3 18:51:55.407: <<<Rcv> Pt:100 Evt:192 Pkt:00 00 00
*Mar 3 18:51:55.411: s=DSP d=VoIP payload 0x64 ssrc 0x1D7C sequence 0x928 timestamp 0x5A6A1EAB
*Mar 3 18:51:55.411: Pt:100 Evt:192 Pkt:00 00 00 <Snd>>>
*Mar 3 18:51:55.431: s=VoIP d=DSP payload 0x64 ssrc 0x1992 sequence 0x18C8 timestamp 0xE6CF45AC
*Mar 3 18:51:55.431: <<<Rcv> Pt:100 Evt:192 Pkt:00 00 00
*Mar 3 18:51:55.571: s=DSP d=VoIP payload 0x64 ssrc 0x1D7C sequence 0x930 timestamp 0x5A6A249B
*Mar 3 18:51:55.571: Pt:100 Evt:193 Pkt:00 00 00 <Snd>>>
*Mar 3 18:51:55.579: s=DSP d=VoIP payload 0x64 ssrc 0x1D7C sequence 0x932 timestamp 0x5A6A249B
*Mar 3 18:51:55.583: Pt:100 Evt:193 Pkt:00 00 00 <Snd>>>
*Mar 3 18:51:55.591: s=VoIP d=DSP payload 0x64 ssrc 0x1992 sequence 0x18D0 timestamp 0xE6CF4B9C
*Mar 3 18:51:55.591: <<<Rcv> Pt:100 Evt:193 Pkt:00 00 00
*Mar 3 18:51:55.599: s=VoIP d=DSP payload 0x64 ssrc 0x1992 sequence 0x18D2 timestamp 0xE6CF4B9C
*Mar 3 18:51:55.599: <<<Rcv> Pt:100 Evt:193 Pkt:00 00 00
*Mar 3 18:51:55.599: s=DSP d=VoIP payload 0x64 ssrc 0x1D7C sequence 0x934 timestamp 0x5A6A249B
*Mar 3 18:51:55.603: Pt:100 Evt:193 Pkt:00 00 00 <Snd>>>
*Mar 3 18:51:55.619: s=VoIP d=DSP payload 0x64 ssrc 0x1992 sequence 0x18D4 timestamp 0xE6CF4B9C

When I did the same debug on the CME it didn't show anything similar. The only activity I got from the call was the VOIP Call history entry:

Oct 19 10:29:32.856: %VOIPAAA-5-VOIP_CALL_HISTORY: CallLegType 1, ConnectionId 9
B493ED7D2EA11E89CF88E9C48714715, SetupTime 10:29:30.436 DST Fri Oct 19 2018, Pee
rAddress 40, PeerSubAddress , DisconnectCause 10 , DisconnectText normal call c
learing (16), ConnectTime 10:29:32.856 DST Fri Oct 19 2018, DisconnectTime 10:29
:32.856 DST Fri Oct 19 2018, CallOrigin 2, ChargedUnits 0, InfoType 2, TransmitP
ackets 0, TransmitBytes 0, ReceivePackets 0, ReceiveBytes 0
Oct 19 10:29:32.856: %VOIPAAA-5-VOIP_FEAT_HISTORY: FEAT_VSA=fn:TWC,ft:10/19/2018
10:29:30.428,cgn:40,cdn:,frs:0,fid:182468,fcid:9B493ED7D2EA11E89CF88E9C48714715
,legID:1FDA9,bguid:9B493ED7D2EA11E89CF88E9C48714715
Oct 19 10:29:45.061: %VOIPAAA-5-VOIP_CALL_HISTORY: CallLegType 1, ConnectionId 8
CBB913BD2EA11E89CE18E9C48714715, SetupTime 10:29:06.541 DST Fri Oct 19 2018, Pee
rAddress 84, PeerSubAddress , DisconnectCause 10 , DisconnectText normal call c
learing (16), ConnectTime 10:29:09.521 DST Fri Oct 19 2018, DisconnectTime 10:29
:45.051 DST Fri Oct 19 2018, CallOrigin 1, ChargedUnits 0, InfoType 2, TransmitP
ackets 0, TransmitBytes 0, ReceivePackets 0, ReceiveBytes 0
Oct 19 10:29:45.061: %VOIPAAA-5-VOIP_FEAT_HISTORY: FEAT_VSA=fn:TWC,ft:10/19/2018
10:29:06.540,cgn:41,cdn:84,frs:0,fid:182462,fcid:8CBB913BD2EA11E89CE18E9C487147
15,legID:1FDA1,bguid:8CBB913BD2EA11E89CE18E9C48714715
Oct 19 10:29:45.061: %VOIPAAA-5-VOIP_CALL_HISTORY: CallLegType 1, ConnectionId 8
CBB913BD2EA11E89CE18E9C48714715, SetupTime 10:29:06.011 DST Fri Oct 19 2018, Pee
rAddress 41, PeerSubAddress , DisconnectCause 10 , DisconnectText normal call c
learing (16), ConnectTime 10:29:09.531 DST Fri Oct 19 2018, DisconnectTime 10:29
:45.061 DST Fri Oct 19 2018, CallOrigin 2, ChargedUnits 0, InfoType 2, TransmitP
ackets 0, TransmitBytes 0, ReceivePackets 0, ReceiveBytes 0
Oct 19 10:29:45.061: %VOIPAAA-5-VOIP_FEAT_HISTORY: FEAT_VSA=fn:TWC,ft:10/19/2018
10:29:06.008,cgn:41,cdn:,frs:0,fid:182460,fcid:8CBB913BD2EA11E89CE18E9C48714715
,legID:1FD9F,bguid:8CBB913BD2EA11E89CE18E9C48714715
Oct 19 10:29:51.089: %ISDN-6-DISCONNECT: Interface Serial0/3/0:3 disconnected f
rom 2564538045 , call lasted 18 seconds

Is there a command that I need to apply to the CME or POTs line to allow those call legs to POTS or between the VG and CME to enter modempass mode?

The VG and CME are connected with SCCP. I understand that if they were H323 there would be a need to do that.

a3b2c1r46 · ‎10-19-2018

That is very good information. Thank you. I did as you suggested and configured both as modem pass-through.

I'm not totally sure the elevation to modem is happening on the CME router here is the out put of the show call active voice:

CME:

110F : 130416 10:14:00.797 DST Fri Oct 19 2018.1 +880 pid:100 Answer 25645XXXXX
active dur 00:00:15 tx:782/130440 rx:781/124024 Tele 0/3/0:23 (130416) [0/3/0.3] tx:13320/13320/0ms g711ulaw noise:-69 acom:29 i/0:-61/-11 dBm

110F : 130417 10:14:00.801 DST Fri Oct 19 2018.2 +870 pid:20052 Originate 34 active
dur 00:00:15 tx:0/0 rx:0/0 Tele 50/0/52 (130417) [50/0/52.0] tx:0/0/0ms g711ulaw noise:0 acom:0 i/0:0/0 dBm

VG202:

Total call-legs: 2
0 : 154 236503450ms.1 +860 pid:0 Originate active dur 00:00:10 tx:531/84024 rx:530/88104 Tele 0/0 (154) [0/0] tx:8320/8320/0ms g711ulaw noise:-53 acom:6 i/0:-11/-64 dBm
0 : 155 236504330ms.1 +0 pid:0 Originate connecting
dur 00:00:10 tx:531/84024 rx:530/83864 IP 172.16.20.1:2000 SRTP: off rtt:0ms pl:6110/0ms lost:0/0/0 delay:65/65/65ms g711ulaw TextRelay: off media inactive detected:n media contrl rcvd:n/a timestamp:n/a
long duration call detected:n long duration call duration:n/a timestamp:n/a MODEMPASS nse buf:0/0 loss 0% 0/0 last 6110s dur:0/0s

Based on this information it appears as though the call leg closest to the fax machine is in modempass mode but the other call legs are in TEL mode. Am I reading that correctly?