Can I reset an FXO using SNMP MIB?
From the CISCO-VOICE-ANALOG-IF-MIB:
-- The ifEntry for an Analog Voice Interface supports the
-- ifGeneralInformationGroup of Cisco IF-MIB.
Hence if you change the IfAdminStatus from up to down to up again, you will have reset the voice port.
Note, that if the FXO port got stuck because of a software bug, the above operation doesn't guarantte it will resume working.
Hope this helps, please rate post if it does!