# Telephony protocol functions

After setting up the ADI service, you must start a telephony protocol
on each context
to perform telephony activities. The NCC service provides a null protocol, NOCC, for applications that do not require call control. Refer to the Dialogic® NaturalAccess™ CAS API Developer's Manual for a list of telephony protocols and parameters and for information about controlling calls under specific trunk control protocols (TCPs).