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 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.