Premium-rate numbers

Premium-rate numbers are used by services such as TV show voting, competition hotlines, directory inquiries, customer service, and chat lines. Calls and texts to these numbers are usually charged at a higher rate than standard calls. 

Example: 

Numbers starting with the following are considered as premium-rate numbers; 
UK - 070..., 087..., 084...., 011..., 089... 
 
Why can't I call these numbers? 

Some of these numbers may have been blocked to prevent bill shock, due to the higher price rates they charge.