I did not see this anywhere on SD, but figured it may be useful to many of
us.
Bobsled: http://www.bobsled.com/
(from T-Mobile) allows you to make unlimited free calls to landline and
mobile phones in USA, Canada, and Puerto Rico. It works on any browser and
most smart phones and tablets.
Hit the link for a detailed review and video tutorial on Bobsled: http://truvoipbuzz.com/2012/01/bobsled-unlimited-free-calls-to-
.