VG224 Fax/Modem Issues

Unanswered Question
Dec 17th, 2008

Hi all - we have 4 VG224's that we are using for analog lines, faxes, modems. Been having a problem intermittently for quite some time with faxes and modems. We will have instances where faxes are dropped or do not go through at all - report back is "poor line condition". We have a modem that we use that we get very poor performance on (even for a modem) - have tried swapping it out and even that does not help. Any thoughts on where to look or what the issue may be? Thanks

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Nicholas Matthews Wed, 12/17/2008 - 12:48

I would add this command:

voice service voip

modem passthrough nse codec g711ulaw

As well, do a 'show call active voice brief' and make sure the lost:X/X/X are all 0's. These are lost/jittered packets, and anything more than 3-4 of these will cause problems for modem/fax.

If these calls are going out of your T1, you will want to check 'show controller t1' for slip/errored seconds. Make sure you've got the network-clock-select command for the T1s.

hth

-nick

zhangjianping Wed, 12/24/2008 - 01:56

sir , i need your help.

Here is my scenario:

CCM(5.1)---MGCP---ISR(VG)

CCM---SCCP---VG224 (ios12.4.15)

The analog phone is ok.

I want to configure modem passthrough or relay, but I don't know how to setup.

The only document i can find in cisco is that to configure below cli in vg224 for relay

'voice service voip

modem relay nse codec g711ulaw gw-controlled'

WHat should i do in ISR and CCM to support modem passthrough or relay?

Because using MGCP between ISR and CCM, so a command in isr is 'mgcp modem passthrough voip mode nse', i tried to change this cli to 'mgcp modem relay ...'

but modem still doesn't work. pls help

zhangjianping Wed, 12/24/2008 - 01:56

sir , i need your help.

Here is my scenario:

CCM(5.1)---MGCP---ISR(VG)

CCM---SCCP---VG224 (ios12.4.15)

The analog phone is ok.

I want to configure modem passthrough or relay, but I don't know how to setup.

The only document i can find in cisco is that to configure below cli in vg224 for relay

'voice service voip

modem relay nse codec g711ulaw gw-controlled'

WHat should i do in ISR and CCM to support modem passthrough or relay?

Because using MGCP between ISR and CCM, so a command in isr is 'mgcp modem passthrough voip mode nse', i tried to change this cli to 'mgcp modem relay ...'

but modem still doesn't work. pls help

Nicholas Matthews Wed, 12/24/2008 - 05:49

On mgcp:

mgcp modem passthrough voip mode nse

mgcp modem passthrough voip codec g711ulaw

no ccm fax protocol cisco

On VG224 SCCP:

voice service voip

fax protocol none

modem passthrough nse code g711ulaw

As well, remove any existing fax commands you tried using.

'show call active voice brief' or 'show voice call summary' should show MODEMPASS as the codec.

hth,

nick

cyoungblut Wed, 12/24/2008 - 06:06

Can this be applied to only specific ports (end-points) on the vg224 or does it need to apply to the whole device? We have a mixture of analog phones, modems and faxes on the vg224. Only having problems with the modems and faxes.

Nicholas Matthews Wed, 12/24/2008 - 06:13

This won't apply for anything except for faxes and modems. This only gets kicked off when the terminating gateway detects the 2100 Hz fax/modem tones.

You can apply this on a dial peer level as well as at a voice service voip level, but that won't help you specify it to a port since this is a voip dialpeer command.

hth,

nick

cyoungblut Fri, 12/26/2008 - 11:36

Thanks Nick, I have applied the commands you listed above...I did not see a change to the config for the codec f711ulaw line but when I did the show call active...I did see that as the codec. also, I have attached my config - would you mind looking to see if you see anything that may be causing my modem/fax issues. this is from one of my vg224s (I have 4) but the other 3 are the same).

Attachment: 

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