This timer, in milliseconds, controls the SSCOP (QSaal) keepalive function on this port, which periodically confirms the signaling connection is still alive during idle periods, per the description. This is the mechanism that lets the port distinguish a genuinely idle-but-healthy link from a silently dead one before real signaling traffic (like a SETUP) would otherwise expose the failure, feeding into the MaxCC loss-of-connection logic if keepalives stop being acknowledged. A shorter TKeepalive detects a dead peer faster but adds more background control-PDU overhead on an already busy trunk.