If you are looking for cheap sim cards for international calls then go to http://www.onepricemobile.co.uk where international calls are one price. You can call USA Land line and Pakistan Mobile for the same price. There is no difference. Fill in your details and get information on sim card for international calls. The best sim for international calls is from one price mobile. If you get the £40 plan you will be able to call Canada and Sri Lanka for one price. The effective price works out at 3.3 pence if you use the full 1200 minutes.
Cheap sim for international calls is possible when the customer does not use all of his inclusive minutes. That is how the large mobile networks Orange O2 T Mobile 3 Mobile and Vodafone make their money. They are so happy when you dont use your full quota of minutes.
The best or cheapest sim card for international calls is a sim that gives you all the calls for one price. That is where you are able to make use of the inclusive minutes to call whereever you want to without any restrictions. How many of you dont use up your full allocation of minutes each month. I too am guilty of that. But now with one price mobile you can easily make calls to 49 countries for one price.