gsm Cs V42 T401 Ack Timer

This attribute specifies the maximum amount of time that the IWF waits for an acknowledgment before retransmitting a frame. Since information about the T401 timer is not carried in the Exchange Identification (XID) negotiations at call setup time, both sides operate with different timer values. The value for T401 depends on many factors, such as propagation delay or frame processing time. A frame is retransmitted up to N400 times if the timer T401 expires before an acknowledgment for a frame is actually received. The performance of the data link layer can be impacted by the value of this timer as retransmissions of frames occur on expiry of timer T401. Changes to this attribute do not effect existing calls.