Since our update in July from 15.0 to 15.5 went so smooth, I decided today to set 15.5 SP1 to automatically install tonight. So I ticked the Automatic Updates box and 3CX PBX updates, set it to Weekly at 22:00 every Thursday. About 5 minutes later I get an email alert: Your 3CX Phone System has been successfully updated! Sure enough, build is now 15.5.3849.1 on my production server. Mystified, my colleague and I then tested on our failover server. Same thing: 5 minutes after setting it for 22:00 every Thursday and the update email came through. As a note, this happened around 14:30 on Thursday.