In Cisco's multichannel interface family, there are versions to support physical connectivity to T3 lines, E3 lines, T1 lines, and E1 lines. For direct termination to E1 and T1 lines, Cisco supports six versions of multichannel interfaces. For sites that require integrated T1 CSU and DSU functionality, the two, four- and eight-port multichannel T1 port adapters provide the right mix of integration and cost. For service provider applications where only DSU functionality is required (for example, at sites colocated with a carrier), the eight-port multichannel DSX1 card provides high port density at a reduced cost per port. For E1 applications, the multichannel E1/G.703 interface allows direct connectivity to 120-ohm G.703 lines.