The Cisco 1 and 2-port T1/E1 Multiflex Voice/WAN Interface Cards ("Multiflex VWICs") support voice, and data applications in Cisco 2600, 2800, 3600, 3700, and 3800 multiservice routers. The Multiflex VWIC combines WAN Interface Card (WIC) and Voice Interface Card (VIC) functionality to provide unparalleled flexibility, versatility and investment protection through its many uses. Customers who choose to integrate voice and data in multiple steps preserve their investment in a T1/E1 WAN interface since the Multiflex VWIC can be reused in packet voice applications.
The T1/E1 Multiflex Voice/WAN Interface Cards are offered in single and dual port versions which can be used and then re-deployed as network requirements change, thereby addressing several applications:

Data-As a WIC for T1/fractional T1, and E1/fractional E1 applications. The 1- and 2- port E1 versions include models that support unframed G.703. To simplify remote management issues the T1 version integrates a fully managed data service unit/channel service unit (DSU/CSU) and the E1 version includes a fully managed DSU.

Packet Voice-As a VIC for the Digital T1/E1 Packet Voice Trunk Network Module (NM-HDV), IP Communication Voice Network Module (NM-HD-2VE), and IP Communication High-Density Voice Network Module (NM-HDV2) to provide T1 or E1 connections to Private Branch Exchanges (PBXs) and central offices (COs) enabling new services and reducing voice/fax toll charges.

Multiplexed Voice/Data-As a dual port T1 or E1 Drop and Insert Multiplexer with integrated DSU/CSUs, reducing the complexity and number of network components and facilitating a graceful migration to bandwidth efficient packet voice.