Had a chance to try out the Bluetooth this morning. Works great for access to voicemail. However, when i tried calling any other valid number, including an extension, other than the one I'm calling from, just after hitting the off-hook button, it went back to on hook. If I call my own extension, it goes off to VM, no problem. Tried this about a dozen times. Then switched back to earpiece to try it again and the phone re-booted itself. Now it's still doing the same thing, going right back on-hook (except VM), but, occasionally it has brought up the profile list, for some reason. It seemed to be working fine the other day.
This is all over 3G, so I don't know if the network is causing these issues. Will try it out over WiFi, at a hotspot tomorrow, although WiFi has worked well in the past, just haven't had the opportunity to try it using Bluetooth.
Never mind...I think I discovered the issue. In an attempt to keep my data usage down I disabled the G711 codecs, leaving just the GSM and Speex. When I re-enabled those it now seem to work (earpiece & Bluetooth) OK. It's funny because I made that change yesterday and had placed several test calls that worked.
I notice that, if you switch off the Bluetooth headset, even though the 3CX phone switches back to the earpiece, Bluetooth still shows on the display.