Here's a sad example.

Just bought some travel insurance from TravelPlan Direct. In an emergency, the policy says you "must" contact +44 (0)870 420 3812.

As I understand it, there are many countries where you can't call to 0870 numbers. So, you've had an accident, you try to call the help line and only then you discover that you can't get through.

You search through the policy for other contact numbers. You've guessed it - they're all 0870 numbers.

The only exception is North America. What do you call if you have an accident there? Right again - a toll-free 800 number.