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Fax over SIP Trunk?

sethschmautz
Level 3
Level 3

Hey guys,

Working on a fax over SIP trunk config and was wondering if anybody else has had any success?  I am using NexVortex as my SIP Trunk provider, and have voice working in both directions on G.729r8 and G.711ulaw.

I (currently) cannot get incoming or outgoing fax to work on either codec (not really surprising on G.729), and have been doing a bit of searching.  I rolled my test UC540 back to a very basic config with SIP trunk using G.711ulaw and was able to see that calls are indeed using this codec.  In addition, I issued the following commands in the CLI:

!

voice service voip

fax protocol pass-through g711ulaw

!

I also saw that you are supposed to unregister the FXS ports with SCCP which I did by issuing the following commands in CLI:

!

no sccp ccm group 1
no sccp ccm 10.1.1.1 identifier 1

!

Am I also supposed to add the following command?

!

sccp ccm 10.1.1.1 identifier 1 version 4.1

!

Thanks in advance,

Seth

14 Replies 14

You have to change your POTS dial peers associated with the FXS ports and remove the "application" command. You will have to add a destination-pattern (which is the fax extension) to this dial peers as well.

Thanks,


Marcos

Hi Marcos,

I hate to ask, but how do you accomplish all of this?  I'm picking up CLI as I go, but could use any assistance that you might have.

Thanks,

Seth

Can anybody else help with the CLI for what Marcos is suggesting?  I will have the majority of the day free to work on this tomorrow, and would love to have this figured out by the end of the day.

Thanks in advance,

Seth

Your POTS dial peers look like this when you are using Skinny:

!

dial-peer voice 1 pots

service stcapp

port 0/0/0

!

They would have to look like this:
!
dial-peer voice 1 pots
destination-pattern 8888
port 0/0/0
!
Where 8888 is you fax extension. If you are mapping a DID to this extension, you will have to manipulate your translation rules as well. This is REALLY EASY with CCA, by the way.

Thanks,

Marcos

Hi Marcos,

Thanks for your time on this.  I try to use CCA for as much as I can and supplement with CLI when needed.  Just so that I understand correctly, when you say "this is really easy with CCA, btw", do you mean that it is really easy to do all of it with CCA or are you saying that it is really easy to manipulate your translation rules to map a DID to this extension?

FWIW, this is cut and pasted from the config that I attached to the original question:

!
dial-peer voice 1 pots
description ** FXS PORT 0/0/0 **
destination-pattern 301
port 0/0/0
!
dial-peer voice 2 pots
description ** FXS PORT 0/0/1 **
destination-pattern 302
port 0/0/1
!
dial-peer voice 3 pots
description ** FXS PORT 0/0/2 **
destination-pattern 303
port 0/0/2
!
dial-peer voice 4 pots
description ** FXS PORT 0/0/3 **
destination-pattern 304
port 0/0/3
!

I currently have the fax machine attached to extension 304.

Thanks in advance,

Seth

Seth,


Can you email me at marchern@cisco.com?

Thanks,


Marcos

Hello Marcos,

Was this issue ever resolved?  I am having the same issue ever since I upgraded our UC520 to 8.0.  The fax was working fine until the upgrade.  Similar to Seth we are using the same SIP trunk provider also.

We found some issues with the configuration, but we could not determine whether these were caused by CCA. Is your system a CCA-only system?

Thanks,

Marcos

No, some configs are done thru the CLI.  Attached are debugs and also the configs that we taken yesterday if you need some reference.

Was there a resolution to this?

I have a few customers faxing over NexVortex SIP trunks with no problems.  One customer is having a problem.

Hi Jason,

Marcos and I came to no definitive conclusions.  My customer base is quite unique, as most of them are using Satellite as their Internet Access.  I believe that this (latency inherent with satellite connectivity) is the source of their problems, and not NexVortex.  If I put the fax machine in "overseas mode", it seemed to work most of the time, but not all the time.  Are your customers using the same model of fax machines at the working and non-working locations?

Seth

Most likely they are using different models.

As a side note, I think incoming faxes are working for the most part with only occasional problems.  It really seems like outgoing faxes are the issue for my customer.

The problem went away after we have upgraded to a newer version of the firmware.

chathuragune
Level 1
Level 1

I would suspect most free internet fax providers have sip faxes.

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