GigPark

“If your cell phone plan has unlimited incoming calls but limited daytime minutes, you can use a "callback service".

You call it and then immediately hang up. Instantly your phone will ring, you answer it and then you can manually dial the number. It's now an incoming call so you won't be charged on your cell phone bill, but you'll be billed by Yak for the time (at a much cheaper rate than cell phone daytime minutes).

I use this when I run out of daytime minutes or when I call long distance, so that I can pay 3.5c/min instead of 35c/min.

http://www.yak.ca/product/yak-cell/how-it-works”