Ring Central

sign-up and 30 days free phone calls

http://www.ringcentral.com/

Free calls to Pakistan

Now you can make 200 minutes of free calls every weak for free. Visit the website below for more details:

http://www.lowratevoip.com/en/index.html

GizmoCall

No need to register from your cell phone, just sign up for free at the website, and start making free phone calls; all you need is, a Broadband internet Connection and a microphone.
HeadPhone.

http://www.gizmocall.com/