If you're a customer of British Telecom (BT) and they are your internet service provider (ISP), then you've probably been sent their standard wireless router the BT HomeHub.
The BT Homehub 2.0 is a very good router. The older Homehubs (white) are not so good. They are old Thomson modem routers and leave a lot to be desired.
The new homehub is wireless n, but not dual band, and does not have an ADSL2+ modem for faster speeds. The older homehubs are wireless g and you may want to replace them.