Let they call you !!!
That's the cheapest way .
I call from Belgium to a cell phone in the DR , and for a call card From 5 Euro I have 70 minuits to call .
My wife rings twice on my phone , so I know that I need to call her . She pays nothing because I don't answer the phone , let him always rings more than twice times , after the thirth ring I know that isn't my wife and I answer the phone .
Wim .