# AP2 and NCC service call control

When applications perform NCC service call control with the AP2 protocol, they can receive digits in the following ways:

Method for receiving digits | Description
All at once | With the AP2 TCP, after NCCEVN_INCOMING_CALL is received, the calledaddr field in the NCC_CALL_STATUS structure contains all received digits. The callingaddr, usercategory and tollcategory fields are NULL. The parameter NCC.X.ADI_AP2.digitnumber determines the number of digits the TCP should expect from the calling party. The default is 7.
One at a time | To receive digits one at a time, make sure the Ncc.Start.OverlappedReceiving parameter is set. The AP2 TCP does not recognize ANI or category digits. Digits are presented in the order in which they arrive. The NCC.X.ADI_AP2.digitnumber parameter determines how many digits to expect.