Mobile calls disconnecting in Lync/SfB

If you notice mobile A/V calls routinely disconnecting in Lync/SfB, check your reverse proxy timeout settings. I use Application Request Routing (ARR) and had the timeout set to the recommended 200 seconds, but found that this was causing all mobile calls to be dropped after this period. Changing the setting to the maximum-allowed 86400 seconds has resolved the problem.

Lync ARR timeout setting