As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CAPTAIN DECLARED AN EMERGENCY ON FLIGHT 2704 DURING THE CLIMB THE CREW REPORTED THE NR 1 AND NR 2 COMMUNICATION RADIO MANAGEMENT UNIT FAILED AS UNABLE TO CHANGE THE FREQUENCY. THE CAPTAIN ELECTED TO RETURN TO DFW. THE AIRCRAFT LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED THE NR 1 AND NR 2 RADIO MANAGEMENT UNITS. THE OPERATIONAL CHECKS WERE GOOD. THE AIRCRAFT WAS RETURNED TO SERVICE.