The type of the current call carried by this DS0.
idle - This DS0 is currently idle.
unknown - The data type of the call currently
occupying this DS0 is not one of the
types listed here.
analog - The data type of the call currently
occupying this DS0 is analog, i.e. a
modem call.
digital - The data type of the call currently
occupying this DS0 is digital.
v110 - The call currently occupying this
DS0 is a V110 call.
v120 - The call currently occupying this
DS0 is a V120 call.
voice - The call currently occupying this
DS0 is a voice call.