I, and many others, received a call from the number about 2am last night.
The call is allegedly from Carrier: Telephony Services Limited or Gradwell. It call is an overlay service which shows as originating from Dunoon, Argyll in Scotland but it could be anywhere in the UK .
There is a trend that it is affecting o2 mobile users so make sure you switch your mobile off at night!
It may also be a premium number so please do not ring back!
There is more information here if you are interested.