How to dial a local number while on roaming with my Vodafone/O2 plan?

When you’re on roaming with your Vodafone or O2 plan and need to dial a local number in the country you’re visiting, instead of dialing directly (e.g., 01234 567890) always use the international dialing format.

Example: If you’re in Spain and need to call a local Madrid number (e.g., 912 345 678): Dial: +34 912 345 678