On Wed, 05 Dec 2012 08:37:04 +0000, Brian Gaff wrote:

I have a feeling these have to be answered calls as well so one cannot
just dial any old number.

Before I moved away from BT Retail, I used to call my doctor's surgery
once every Sunday morning in order to make the required number of calls
to keep Caller ID free. Weekend calls to 01/02/03 numbers were free, and
the surgery (being closed) answered the call with a recorded message.