The Cisco VWIC2-2MFT-T1/E1 Voice/WAN Interface Cards support data applications on the Cisco MWR 1941-DC Mobile Wireless Edge Router for T1/E1 networks. These cards are dual-port, T1/Fractional T1 or E1/Fractional E1, Drop and Insert Multiplexers with integrated T1 CSU/DSUs or E1 DSUs. The T1 version supports framed and unframed traffic, and the E1 version supports framed traffic and unframed traffic that conforms to the ITU-T G.703 standard for full 2.048 Mbps bandwidth.

The Drop and Insert multiplexer diverts (drops) streams of an aggregate Time Division Multiplexed (TDM) traffic stream, and introduces (inserts) different streams for transmission in the time slots that were previously occupied by the dropped streams. Each VWIC supports a limited channelized capability where the T1 or E1 can be flexibly split into two fractional channel groups, one on each port or two on one port. The switching operation can be maintained through router restarts and reloads of Cisco IOS software.

Each card also features protection switch solid state relays on the line interfaces, which together with redundancy logic and relay control added in a Cisco IOS feature set on the MWR 1941-DC router, can be used to provide T1/E1 Protection Switching between redundant routers in applicable implementations.