Just to prove it can be done.

[#1]

79 days continuous sync! It would have been longer if it wasn't for a local power failure. Get your line right and it works - nowt wrong with PN, it's BT's system that's the problem.

[#2]

79 days isn't very long....
We are often into hundreds of days here - but sadly I'm in the process of moving all our phone sockets around the site.
Ours is currently a paltry 144hrs.
PN might be able to reveal the longest times out of their DB.

[#3]

It used to be very long for me James! But that was before the line was given a good hard talking-to!