With yak4ever you can call any international number in the world from a United States landline or cellphone (or any phone of that matter.)

How yak4ever works?
You signup for the service, and enter ten numbers (from anywhere in the world) that want to call from your home phone. You assign a number 1 to 10 on your yak4ever calling account. Once you complete registration you will be able to call any one of those ten free numbers using your cell phone.

Best way to make free international phone calls?
It works great if you need to call internationally from a cell or home phone. Unfortunately you there is no software to download so it won’t work with your computer.