UK, Ireland / Calling a friend from UK to Poland. Cheap option? [13]

I am trying to Phone a friend who is in Poland (I am in UK). I am on T-Mobile PAYG, and have no problem phoning any other phones abroad. However when I try and phone Poland it rings and then the connection is lost. Could it be the person doesn't want to pick up and disconects or a problem with my network? I can text and recieve replys but the problems occur when phoning. Any help or information would be great thanks.

P.s This is my first post!