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The Lead Timeout will show you how long an agent can have a lead open until it timeout. When the lead timeout, it will promt the user to the Feed page
The Dialing Number Threshold: would not let you call a number twice between a specific amount of seconds, so the amount of seconds in this section stand for the time limit between the calls for a specific number
Engine
This should only be use when you are experiencing problems or slowness with the feeding page (loading a lead, dispositioning a lead or direct viewing a lead)