Abstract: A method for testing a voice gateway includes the operation of transmitting a first series of network packets containing test data from test equipment to a network interface of the voice gateway. After the test data has been converted by the voice gateway from a network format to a telephony format and then converted back to a network format, the test equipment receives a second series of network packets containing the test data. The test equipment then analyzes the test data in the second series of network packets to determine performance characteristics of the voice gateway. The operation of analyzing the test data may include the operation of identifying bytes from the test data with byte values that represent idle insertion by a telephony interface and/or the operations of determining elapsed time between transmission and reception of the test data by the test equipment.