If you were to call 08453 373 183 it is answered by a recorded message saying that they are ICM Research and  "we called you earlier and may call you again".  

It is a market research company whose computer randomly dials phone numbers and if no operator is available to talk you get silence. Their website is http://www.icmresearch.co.uk/. They also say that if they call again and you don't want to take part in the market research just say so.

Alternatively, the purpose of their call may be to induce you to call back and they then collect the revenue from the 0845 call.