Functionality:

Holding down the call key for eight seconds while the headset is off will put it in pairing mode, which is indicated by blue-red flashing of the LED. Searching through your phone, it will be indexed as 645Plantronics and for connecting to it a usual 0000 code should be entered.

Operating the headset is done by rather strange key combinations. In standby mode, single press of the call key won’t do anything but beep, while holding it for two seconds will bring the voice commands menu up. In order to activate last number redial, you should double click the call button.

Answering an incoming call is done by single press of the calling key, while rejecting it is done after holding the key for eight seconds, which is pretty sluggish method. If the headset is in the cradle, it will start vibrating on an incoming call. Getting the headset out of it will automatically answer the call, and getting it back will hang up.

*-In order to mute the microphone during a call, a simple pressing of the both volume keys at the same time should be performed. This is relatively easy operation. Be careful, as doing this in standby mode will enter in “power saving mode” which turns off the DSP system until you start it again. Unfortunately the latter doesn’t give any real indication, as just a simple beep is heard – the exactly same beep is heard when turning it back on, and by doing this you won’t be able to know if you power it on or off.


Performance:

During a call the performance of the 645 is above the average but it is not anything special. Relatively strong volume is obtained in both directions, and the voices sound realistic and clear, but a little muffled and monotone. The DSP system is not the best in windy environment, but handles well with music and other sounds around you so you can use the headset in noisy places. *The DSP is supported by Plantronics 645 only and not by 640.