188.8.131.52.3 Delayed-Ack Timer
As described in [C706] section 184.108.40.206, a client can implicitly acknowledge receipt of response by sending a new request to the server. The Delayed-Ack Timer creates a window where a higher-layer protocol can submit a new call, which will be sent instead of an ACK PDU. The new call might be already queued in the activity's List of Active Calls (see section 220.127.116.11.1.5) or might be initiated during the timer's window. The activity's Delayed-Ack Timer MUST be started when the activity's current call enters Call State STATE_ACK_PENDING. The timer MUST be canceled when the client initiates another call by using the same Activity.