A few alternatives, Fring is a very similar service that, like Skype, allows for voice calls and video calls, often at a price lower than Skype’s.
Google Voice I recommend it. Not only does it give you free and low-cost calls, but it also provides a rich suite of services, like voicemail and call forwarding.
Then there is a free voice-only service called Freephone2phone. This service give users a free 10-minute call to any of 55 countries, but they have to listen to an advertisement or two first. To use it you first have to look up a local number on the Freephone2phone Web site, dial, and listen to the ads. Then you can dial the number you want to reach. You’ll get warning beep 30 seconds before your 10 minutes is up.
There are dozens more, which can be found through sites like truVoipBuzz.com or VoipNow.com.