Ok, not had much luck with problems previously, but I'll have another go! I purchased an Aastra 6739i for my 3cx system (lovely phone, btw) and successfully auto-provisioned it from 3cx. All seems to work fine, except the blf soft keys. They seem to work fine, lighting up when someone goes on a call - but then they never go back to "on hook" status. They simply remain as if the person is on a call forever. I double-checked on MyPhone and in the management console and the extensions were shows as not on a call. The keys are autoprovisioned from 3cx for internal extensions and the Aastra phone web console shows them as configured as "BLD/Xfer" keys. The phone's firmware is version 18.104.22.168.