Timer T303 is the Q.93b protocol timer, in milliseconds, that governs how long this port waits for a CALL PROCEEDING, CONNECT, or RELEASE COMPLETE reply after transmitting a SETUP message to establish an SVC. Network engineers care about this value because if it is set too short relative to real call-setup latency on this switch, legitimate SVCs will be torn down and retried before the far end can answer, driving up the svcAtmFailedCall table and the setup-PDU retransmit rate; too long, and a genuinely dead call hangs the signaling channel longer than necessary. A typical configured value is 4000 milliseconds, and lowering it to something like 1500 on a congested trunk would likely start generating spurious call failures.