I have made extensive researches on the subject: I have examined forum threads back to 2008 and looked at almost all the websites which have been suggested as well as the hint that were provided.
Many websites advertise free calls but they are using misleading advertisement for in the end they do not give anything away. Some will offer free minutes only if you bring in new members, which is equivalent to pyramidal sales. In the long run, I have found that Skype has the cheapest rates and the very best service so far for calling.
In conclusion, I suggest that it is useless to search how to make free calls. In this world nothing is free except breathing and yet, will come a day when we will be taxed for it.