Fax Configuration and Troubleshooting Project

[Abu Hadee]

FAX over VOIP some times can be challenging. Finding the right configuration is sometimes difficult as it can be SCCP, MGCP, SIP or H323 or even combination of multiple protocol. More over, it can be fax pass-through, T38 or Cisco fax relay. 3rd party Fax Server in the IP side makes the situation a bit difficult.

I've created a project to find the working configuration of FAX in different combinations which is running on your network. Submit your topology and requirement along with protocol to use, we will test in lab.  We will submit the configuration along with debug and troubleshooting tips for your reference if something goes wrong.

Click Here to check the progress and submit your requirement. Hope this will help you.

Waiting for your submission.

Thanks

- abu

[Asim ali]

Hello,

am facing a strange problem with FAX on ATA. I have CME on 2851. I dont get FAX tone when i dial into ATA connected to FAX machine,  But i can send Fax without any problem from ATA. Receving FAX is the problem. Even for voice call also, i connected a phone to ATA and i can call outbound from ATA. but when i dial  into ATA i dont hear any thing, Ring goes, when the call is answered there is silence, no body hears anything. For Fax also same thing, i can see fax machine picking up incoming call but nothing happens.

I have SIP inbound from Telco.

My dial peer for incoming calls from  Telco.

dial-peer voice 444 voip
description  ***FAX***
destination-pattern 2871023
modem passthrough nse codec  g711alaw
session target ipv4:192.168.12.22                   (ATA  IP)
fax rate disable
no vad

voice service voip
allow-connections h323 to  h323
allow-connections h323 to sip
allow-connections sip to  h323
allow-connections sip to sip
fax protocol t38 ls-redundancy 0  hs-redundancy 0 fallback none
modem passthrough nse codec  g711alaw

My ATA is h.323 end point.

Connect Mode 0x90000404

Audio Mode is 0x00000015

I saw the call history it shows incoming call with  g.729. But I don’t have this codec any where. I feel due to  this reason

am not able to receive. For  outgoing from ATA I see both call legs on g.711alaw.

3131 : 124936 1097223000ms.10593 +2440 +19250 pid:3232  Originate 6745831
dur 00:00:16 tx:831/132960 rx:841/134560 10  (normal call  clearing (16))
IP 10.302.1.5:26862 SRTP: off rtt:0ms pl:0/0ms lost:0/0/0  delay:0/0/0ms g711alaw TextRelay: off
  media inactive  detected:n media contrl rcvd:n/a timestamp:n/a
  long duration call  detected:n long dur callduration :n/a timestamp:n/a

2CAD : 124950 1097333830ms.10594 +-1 +46910 pid:444  Originate 2871023
dur 00:00:00 tx:0/0 rx:0/0 10  (normal  call clearing (16))
IP 0.0.0.0:0 SRTP: off rtt:0ms pl:0/0ms lost:0/0/0  delay:0/0/0ms g729r8 pre-ietf TextRelay: off
  media  inactive detected:n media contrl rcvd:n/a timestamp:n/a
  long duration call  detected:n long dur callduration :n/a timestamp:n/a

Any ideas please.

[Francisco Manuel Oliveira Garcia]

hi

Have you tried with setting an incoming dial-peer to force g711alaw?

same thing like this

dial-peer voice xxxx voip

incoming called number 2871023

codec g711alaw

[Asim ali]

Hello @ Fuko

Yeah i have tried it already, but still it wont work.

[Francisco Manuel Oliveira Garcia]

did you set fax rate disable to the incoming dial-peer?

Ata devices are very hard to make it work. My experience is using sccp protocol and the problems found always were related to codec missmatch, paquet loss. Audio Mode or Connect Mode can be changed however I have several atas working with diferent configurations with the same fax model.

for voice calls a missmatch betwen g711ulaw and g711alaw is not a problem but for a fax call, faxes can be send in one direction and fails in the other.

I hope it brings you a bit of light to the problem.

regards.

[Abu Hadee]

Hi Asim

I'll try to find the correct configuration.

Thanks

- abu

[Thomas Rouillard]

http://www.cisco.com/en/US/products/hw/gatecont/ps514/products_configuration_example09186a00800d698e.shtml?referring_site=smartnav

try this doc  - hope it helps

[Asim ali]

@Thomas

I have been through this document many times, but it wont help. Actually i found every body saying as the config being pretty straight forward, but for some reason it wont work with me.

I will test this with SCCP image tommorrow and will see how it works.

[Thomas Rouillard]

Hi Asim - Are the fax calls coming in on a SIP trunk from the PSTN, or a ISDN PRI? I would be happy to look at your config if you want me to. Also - I have this working with codec g711ulaw, not g711alaw.

[Asim ali]

Dear Thomas,

The Fax calls are coming on SIP trunk from PSTN. The codec G711alaw is what my PSTN sends me. They have a policy where they wont pass other codecs, so i have to stick with G711alaw.

I will be happy to send you my config. FYI below is my dial peer info.

dial-peer voice 444 voip
description  ***FAX***
destination-pattern 2871023
modem passthrough nse codec  g711alaw
session target ipv4:192.168.12.22                   (ATA  IP)
fax rate disable
no vad

voice service voip
allow-connections h323 to  h323
allow-connections h323 to sip
allow-connections sip to  h323
allow-connections sip to sip
fax protocol t38 ls-redundancy 0  hs-redundancy 0 fallback none
modem passthrough nse codec  g711alaw

Thank YOU

[Abu Hadee]

Hi

Since the PSTN is over ISP, I am assuming that they only support T38. On other hand, ATA may only support fax passthrough. So, you may not get working scenario. So the best bet for you will be fax in voice mode. So, remove the fax or modem passthrough from both ATA and provider dial-peer. Let it be purely g711 on both and try it.

Let me know how it goes.

[Abu Hadee]

Hi All

This blog is to collect different scenario of FAX. So far following has been collected

1. SIP Provider ------SIP ------------CUBE---------H323 -----ATA

2. PSTN--PRI---GW-----MGCP----CUCM----SCCP---VG--fax

3. PSTN--PRI---GW---SIP---CUCM---SCCP---VG-fax

4. PSTN--PRI---GW-----MGCP----CUCM----MGCP---VG--fax

5. PSTN--PRI---GW---SIP---CUCM---MGCP---VG-fax

6. PSTN--PRI---GW-----H323----CUCM----SCCP---VG--fax

7. PSTN--PRI---GW---H323---CUCM---MGCP---VG-fax

let me know if you have any other scenario to add to it.

Thank you all for participating.

- abu

[Francisco Manuel Oliveira Garcia]

Hi Abu

I think you should add cisco fax server.

I am currently working on the following scenario

PSTN-PRI--GW--MGCP--CUCM------h323------cisco fax server (RigthFAX)----MS Exchange

I am also interested in check the above scenario in fax server redundance  mode

regards

[MMstre]

Hi Abu,

I am working with a CME and VG224.  CME is controlling VG224 using SCCP.

Topology is

PSTN--2xPRI--CME--SCCP--VG224--Fax

I have tried many different combinations and the devices dont seem to want to cooperate.

Kind Regards,

Mike

[Asim ali]

Well i have just fedup with this fax on h.323.

Tried this by converting FAX image from h.323 to SCCP. worked like charm, no configuration was needed absolutely on gateway, just add dn to the fax and there you go....

SIP (PSTN)--  GW -SCCP--FAX

Regards

[metalium2007]

Hello,

I would like to interconnect a Cisco Router ISDN card with Brooktrout TR1034+P2-1B (BRI). Since I need to give L1 clock from the Cisco side, is this a possible scenario?

Thanks!

met