Digipeaters act as simplex repeaters, receiving, decoding and retransmitting packets from local stations. Reliability is achieved by the sender detecting lost data and retransmitting it. Unlike other FM stations, the CHOU-1-FM 104.5 FM retransmitting signal is in mono. The end points have the responsibility for detecting and retransmitting dropped frames. Barreiras has one retransmitting television station, three radio stations, and several newspapers. ZMODEM could also resume interrupted transfers without retransmitting the already-received blocks.