Abstract: An embedded echo canceller in a wireless network is tested by routing traffic signals through the echo canceller and measuring input and output signals of the echo canceller as it operates to remove echo signals from the traffic signals. To test the operation of the echo canceller in regards to a plurality of hybrid circuits, a hybrid interface box controlled by an echo canceller test program is attached to an upstream end of the echo canceller. An ISUP communication is established between two wireless units, through the echo canceller and a loop around trunk. The communication is traced, and a traffic channel portion of the communication (separate from a signaling channel) is broken. Because the two channels are separate under ISUP, this does not terminate the communication. The hybrid interface box is controlled to inject test signals into the traffic channel, and the operation of the echo canceller is measured.