Why wouldn I buy a Plantronics wideband headset?
If you do not have a wideband phone you do not want a wideband headset, unless you are expecting to change fairly soon. The extra bandwidth that a wideband headset offers is only of value when you have a wideband phone that supports it. In fact, there may be audio artifacts (noises) from the network that may be heard if you use a narrowband phone with a wideband headset.