(Voice Over DSL) Sending voice over a DSL line. Using compression, up to 150 voice channels can be transmitted over a 1.5 Mbps DSL line. DSL signals at the customer side are delivered into an integrated access device (IAD), which forwards them over twisted pair to the carrier. The signals go to the carrier's DSLAM and then to an access switch that forwards voice to a voice gateway and then the PSTN and data to the appropriate data network.