This read-write value sets the number of seconds between successive attempts to establish the backup trunk call, within a single call-setup cycle governed by lportBuTrkRetryNum. An admin tunes this based on how quickly the backup path, often a dial-up or switched connection, can realistically be retried without overwhelming the far end or the switching network with retry attempts. For example, setting lportBuTrkRetryInt to 15 seconds means if the first backup call setup attempt fails, the switch waits 15 seconds before trying again, up to the configured lportBuTrkRetryNum limit.