Method and apparatus for fault isolation by a communication system tester

A method for testing a unit under test, said method performed by a communication system tester coupled to said unit under test, said method comprising the steps of:

• transmitting by said communication system tester a stored message to said unit under test;
• determining by an operator whether said stored message is output on a speaker of the unit under test;
• inputting by the communication system tester an audio signal selected by the operator to the unit under test, if the operator verified that said stored message was output on the speaker of said unit under test;
• sending back by said unit under test a processed audio signal to the communication system tester, said processed audio signal being derived from the audio signal;
• capturing by the communication system tester the processed audio signal;
• transmitting the captured, processed audio signal to the unit under test;
• and
• determining by said operator whether the captured, processed audio signal was properly produced on a speaker of the unit under test.