Book:OTRS 3.0 - Admin Manual/Chapter 8/2

Locked tickets can be automatically unlocked by the system. This feature might be useful if, for example, an agent has locked tickets that need to be processed, but he can't work on them for some reason, say because he is out of the office on an emergency. The automated unlock feature unlocks tickets after a given time to ensure that no locked tickets will be forgotten, thereby allowing other agents to process them.

The amount of time before a ticket is unlocked can be specified in the queue settings for every queue. The module bin/otrs.UnlockTickets.pl, which is executed periodically as a cron job, performs the automated unlocking of tickets.

Notifications on unlocked tickets are sent out only to those agents that have the queue with the unlocked tickets set in "My queues", and that have activated the notification on unlocked tickets in their personal preferences.

Tickets will be unlocked if all of the following conditions are met:
 * There is an unlock timeout defined for the queue the ticket is in.
 * The ticket is set to locked.
 * The ticket state is open.

The unlock timer will be reset if an agent adds a new external article to the ticket. It can be of any of the following types: email-external, phone, fax, sms, or note-external.

Also, if the last article in the ticket is created by an agent, and a customer adds another one, either via web or email response, the unlock timer will be reset.

The last event that will reset the unlock timer is when the ticket is assigned to another agent.