Hi all, I like Aaron's proposal for calculating timings, so I have attempted to draw this out as a timing diagram - see attachment. I have made some changes - 1. I assume that the goal is to provide some guarantee for connection availability at the user's requested start time 2. Similar guarantee for availability up to the users' requested end time 3. I have added a margin as proposed by Jerry. Please take a look at these timing diagrams and let me know if they make sense to you. Guy