This read-only string reports the accumulated call time for every port on the gateway, packed as a comma-delimited list in port order. Admins scan it for ports whose call time looks disproportionate to their call count, which can hint at hung or abnormally long-held calls tying up a specific port. For example, a port showing a call time far higher than its neighbors despite a similar call count in gwnumberOfCalls could indicate a stuck call never properly released.