It's actually called an Oryx Portasol and the design of it hasnt changed since it was introduced probably 15 years ago - it was orginally developed by a couple of Irish brothers who worked for Bosch on their handsfree hair curlers, it uses the same technology.
I used to be a development enginer for a company called Greenwood Electronics in Reading who had the worldwide rights to sell them - and they sold zillions and zillions including some branded ones for BT
http://uk.farnell.com/jsp/Mechanical,+Offi....jsp?sku=070421
And i think they are cheaper now than way back then.