here's the thing..

I donno about other calling services but i do know about Skype. I have the same thing going on, i have a friend who's got a cyber back in KTM and i got him a Skype account in my name and make monthly payments on it.
Basically i got an unlimited subscription that allows calls to be made in a number of countries for a monthly cost of $10/month which back home is ..750 NRs give or take a few hundred ...and you add a little profit of your own..and say total it out to a 1000 Nrs a month.

Now he gets  unlimited phone calls to most countries as US, Canada, UK etc for 1000 NRs (more if you increase ur profit margins) and depending on the traffic he gets at the store, makes a profit or not...either way your folks back home get a 1000 bucks  every month and a friends gets his business.

BUT, you do need a friend or a guy you trust..coz you might keep the end of your bargain and he might not..
Besides that, it's pretty okay.

Hope this helps.
Check out: http://www.skype.com/allfeatures/subscriptions/uscanadaworld/ for more details.