Need top up to call a business number

Even though I had 100 minutes of UK calls in credit I was not able to make a call to a UK business number. I am still shaking my head over this? I never considered it would be necessary to distinguish from business or social number. I guess this is buried in the T&Cs somewhere...who knew?

If the business number is chargeable and not standard rate then it wont be covered in your allowances Wyerichard.