If you mostly need incoming and your outgoing to US is less than 300/minutes a month
Buy an incoming number form localphone(http://www.localphone.com/) for $1/month (2 cents/min to india)
and configure it on a device which connects to your internet router. E.g. http://www.localphone.com/help/voip/devices/linksys/pap2
The cheapest device I could find is Linksys PAP2. On eBay it is available in the range of $30 with shipping.
I have been using localphone for quite some time and it is good.
If you need heavy outgoing minutes and CANNOT keep your computer on all the time
Skype Costs $5/month for unlimited outgoing to US plus an incoming number.
Search for “skype hardware without computer”
If you need heavy outgoing
minutes and can keep your computer ON all the time.
There are many solutions.
http://www.magicjack.com/6/index.asp
search for “skype hardware” on google and you will find a ton of solutions.
If you want to use your wifi enabled cell phone to talk to google/skype/yahoo/msn friends.
CP