As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CABIN INTERPHONE INOP TO COCKPIT. SAMC TEXT: SELECTED CI TO ALT, WORKED FOR A COUPLE MINUTES THEN FAILED. COCKPIT GETS BUSY SIGNAL. REPLACED PA-CABIN INTERPHONE CONTROLLER & AMU PER MM. RESET O2 MASKS & MINITELS IN FLT DECK. SYSTEM RESTORED TO NORMAL.