The Cisco MC3810 with the DVM provides support for up to 24 voice channels, one for each voice port. Depending on whether the controller is T1 or E1, different DS0 voice channels are used. The DVM supports Channel Associated Signaling (CAS) for the following types: FXO, FXS, and E&M. For E&M signaling, the DVM also supports E1 Mercury Exchange Limited Channel Associated Signaling (MELCAS).