Step by step manual:
1.Downoald the app
2."Park" your local number
3.Start up the programme before departure
4.Buy a sim card in your destination country
5.Enter the app.
Frankly was a bit nervous about how the app. will work, not much into technical/app kind of stuff. But it turned out to be as easy as ABC!
(Finding my manual above you can make sure of it). Buying a sim card can be the only perplexing step. Variety of operators, different use environment, all kinds of prices can easily puzzle anyone. I bought the cheapest card which costed only 5 euro, added 5 on account and for a week stay in Greece it was more than enough. I had incoming calls from Ukraine and Germany, both incoming and outcoming from Greece, wrote text messages.
From now on Roamer is my travel mate!