Cisco IAD 2421 - Router - VoIP phone adapter - DSU/CSU - EN, ATM, HDLC, Frame Relay, RS-232, PPP, RS-530, X.21, V.35, RS-449, MLPPP - Cisco IOS - 1U

The Cisco IAD 2420 series integrated access device (IAD) aggregates multiple channels of data and voice/fax user-side traffic for transport over a single wide-area network (WAN) uplink. Voice/fax traffic is transported by Voice over Internet Protocol (VoIP) or by Voice over Asynchronous Transport Protocol (VoATM).