My second post here (first was really a non-post)..
If you are looking to call international destinations for cheap, then Lyca mobile is offering a free SIM and starter pack. Order it online via the link provided. To some countries, especially Asian countries, the calls are free :) with only a 19c flagfall. How good is that!!
Lots of countries in there so can't detail here but just check out the link and order your free pack. Ordering area to the right hand side of the webpage.