Question : ECHO IN CISCO PHONE SYSTEM

WE HAVE CISCO IP PHONES IN THE OFFICE. ONE PF OUR EXECUTIVE HAS SOME PROBLEM WITH HIS PHONE SYSTEM.I REPLACED HIS OLD 7961 PHONE WITH NEW 7971 PHONE AND THAT DIDNT WORK FOR US AND THEN I DID SOME VOLUME CONTROL SETTINGS ON THE PHONE AND IT DIDNT WORK FOR US EITHER. EVEN WE CHANGED HIS LLINE WITH NEW ONE BUT DIDNT WORK. HE DOESNT HEAR ANY ECHO IN INTERNAL CALL'S. HE ONLY HEAR ECHO FROM OUTSIDE CALLS WHEN PEOPLE CALL HIM.
PLEASE HELP.

Answer : ECHO IN CISCO PHONE SYSTEM

Check the PRI circuit (for external calls)  on the call-manager cluster.