A calling card is a way to buy service / minutes from a different telephone company.
There are several benefits of buying minutes from another telephone company, even when you already have a telephone company service via land line or a mobile phone:
1. Better access in many cases.
2. Cheaper than many other telephone companies.
3. One flat per-minute rate, day or night, weekends or weekdays.
4. Easy to use.
5. The ability to control how much you spend on international calls.
