# Acknowledging a PRACK

To acknowledge a PRACK, use nccSendPrackResponse.

#### Prototype

DWORD NMSAPI nccSendPrackResponse ( NCC_CALLHD callhd, void *prackresponseparms)

Argument | Description
callhd | Call handle returned to the application with the NCCEVN_SEIZURE_DETECTED event.
prackresponseparms | NULL or pointer to a buffer containing SIP IEs.

#### Details

In the SIP protocol, a PRACK is acknowledged by 200 OK message. A possible message sequence would be: the called side sends a 180 RINGING response, this is acknowledged by a PRACK, which in turn is acknowledged by a 200 OK response.

If the SIP stack is configured with nccSendPrack enabled, then nccSendPrackResponse is automatically enabled. If the application receives an NCCEVN_PRACK_INDICATION event, it must acknowledge the PRACK by calling nccSendPrackResponse.

#### Example

ret = nccSendPrackResponse( callhd, NULL );