Fax issue post upgrading 2821 to 2921 H.323 gateway

[Aaron Denny]

Recently upgraded a gateway from 2821 to 2921. Voice config did not change at all on the ISR.

Faxes coming in and out of the PRI are failing on fax machines that are on VG-224s only. Fax machines on ATAs have no issue.

I tried changing the settings from passthrough to relay on the VG-224 with no luck. Any ideas on where to start? Thanks in advance.

[Chris Deren]

Fax relay is not supported on PVDM3s which is probably what changed for you when going from 2821 to 2921. Can you post your relevant config from the router and VG224?

Chris

[Aaron Denny]

2921 Config

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 version 0 ls-redundancy 5 hs-redundancy 2 fallback pass-through g711ulaw

h323

sip

  bind control source-interface loopback1

  bind media source-interface loopback1

!

voice class codec 1

codec preference 1 g711ulaw

codec preference 2 g729r8

!

voice class codec 2

codec preference 1 g729r8

!

voice class h323 1

  h225 timeout tcp establish 3

  call preserve

VG224

voice service voip

fax protocol t38 ls-redundancy 5 hs-redundancy 2 fallback pass-through g711ulaw

!

ccm-manager fax protocol cisco

ccm-manager music-on-hold

ccm-manager sccp local FastEthernet0/0

!

mgcp fax t38 ecm

[Chris Deren]

So, it looks like you are using protocol based T.38, however your VG224 is not properly configured for protocol based T.38 as you are missing the following:

mgcp package-capability fxr-package

mgcp default-package fxr-package

These two commands are needed to go from the default configuration of NSE-based T.38 to protocol-based T.38.

The command no mgcp fax t38 inhibit is required for both NSE and protocol-based T.38, but it is the default.

HTH,

Chris

[Aaron Denny]

Chris,

The following fixed the issue for us. Previous config in 2821 didn't work on 2921. Thanks again for your posts!

Aaron

***Added the following to 2921 and VG224 configs.

voice service pots

fax rate disable

!

voice service voip

fax protocol none

modem passthrough nse codec g711ulaw

***VG224 set to Fax Passthrough and Modem Passthrough Enable in CUCM.