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FAX configuration MGCP 2911 Router FXS PORT CUCM 11.5

FXS Port configuration for FAX  MGCP 

We have a 2911 router with MGCP configuration with 4  FXS port  . FXS port connect the fax machine directly to it. How would I configure the FXS port to support this on router and CUCM.

2 Replies 2

Sreekanth Narayanan
Cisco Employee
Cisco Employee

It depends on the fax protocol that you'd like to use for fax calls made to and from this port. 

MGCP supports fax passthrough (nse based fax switchover) and T.38 protocol based fax.


If you are using T.38, then you can configure the MGCP router with these commands:

no ccm-manager fax protocol cisco
no mgcp fax t38 inhibit
mgcp package-capability fxr-package
mgcp default-package fxr-package
no mgcp fax t38 ecm
mgcp fax t38 nsf 000000

Re-register the Gateway with CallManager by entering the following commands :

no mgcp


If you are using nse based switchover to fax, then configure the router like this:

no ccm-manager fax protocol cisco
mgcp modem passthrough voip mode nse
mgcp modem passthrough voip codec g711ulaw


Note that the gateway/CUBE that routes calls to and from the PSTN also has to be configured with the same protocol for fax. Else, the switchover from voice to fax call will fail and the fax signals will be transmitted over regular RTP.

Cisco Employee
Cisco Employee
Remember, if you have a CUBE, your only option is T.38 since your ITSP won't support an NSE protocol simply because it is proprietary. They might if they have Cisco gear terminating these faxes.

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