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VG224 - analog fax cannot receive, just send

Level 1
Level 1

Hello Together,

I am running a vg224 in CCM 6.1 environment. It is bind to CCM with the sccp protocol. At the moment our faxes are not able to receive faxes, which are originated from an other Cisco Voice GW.

Receiving faxes from PSTN are working fine.

Senting faxes to a PSTN Fax or to a fax device on another site is possible. The other site hide their fax devices behind a cisco gw too.

cut from config:

voice service voip
modem passthrough nse codec g711ulaw

voice-port 2/9
cptone DE
timeouts ringing infinity
caller-id enable

dial-peer voice 99939 pots
service stcapp
port 2/19

Thanks for support!

4 Replies 4

Level 1
Level 1


Did you ever solve this issue?

I have a CUCM 7.1.5 and I'm facing the same issue with my VG224


Ahmed El-Eraky

Christopher Graham
Cisco Employee
Cisco Employee

Can you be a bit more specific regarding your call flow?  For example:


You mentioned that you are able to receive inbound faxes from the PSTN, correct?  Is the sending fax machine in your failed scenario attached to the pstn gateway?  I'm just trying to get a feel for any differences in network topology for the working vs. non-working scenario's

Can you post the relevant config for the sending fax gateway as well?  Keep in mind that the fax transport method for the originating and terminating gateway's must be the same.

Also, please provide your IOS versions, as an IOS bug is not out of the questions.

If you can, run the following command on the originating gw and the vg while the fax is transmitting:

'show call active voice br'

You'll need to run the 4 or 5 times to make sure we get all pertinent info (dropped/early/late packets, delay, proper switchover, etc)

Mike Lydick
Level 1
Level 1

I would consider enabling T38 on the MGCP gateway and on the SCCP gateway.T38 will be more reliable.


- IOS gw -

voice service voip

fax protocol t38 nse ls-redundancy 0 hs-redundancy 0 fallback

(MGCP/T38 section)


Gateway should have T38 and modem passthrough enabled

- IOS gw  -

no mgcp fax t38 inhibit

- IOS gw -

do show mgcp, look for the fxr-package is disabled (cisco Fax relay) and look do see that t38 is enable

Regions should be set for g711 between devices.

While the fax is being negoitated, sho voice call sum repeated will allow you to see the call transition from g711 to t38.


Was this ever resolved? I am having problem with the fax line too.


I have fax machine connected thru VG224(SCCP) I can send but can't receive fax. My MGCP T.38 is Disabled. How do I enable this.

And do I need to have this command in MGCP gateway as well?

voice service voip

fax protocol t38 nse ls-redundancy 0 hs-redundancy 0 fallback