The new price plan is called the Eastern European Pass and offers reduced rate calls to nine countries including Croatia, Czech Republic, Hungary, Latvia, Lithuania, Poland, Romania, Russia and Slovakia.
Calls to landlines in these countries will cost 5p per minute, while calls to mobiles will be charged at 15p per minute.
T-Mobile customers can join the new price plan by texting INT to 441, the text is free and there’s no connection fee or access charge for joining the service.
T-Mobile head of Pay As You Go Chris Barrow said: "Whether friends and family are around the corner, across the country and now even in Eastern Europe, we’re making sure that our customers can keep in contact.
“With the Eastern European Pass, customers can now do this for a fraction of the cost and with our normal UK Pay As You Go rates they know they are continuing to get great value when making UK calls."
T-Mobile has also launched a new web’n’walk 5 Day Pass, which offers customers unlimited mobile Internet access for £2.50.
T-Mobile head of Internet on the Move Richard Warmsley said: "The web’n’walk 5 Day Pass puts the whole internet into your pocket. It’s perfect for people who simply want to dip in and out of the internet on their phone, with the 5 Day Pass you get unlimited web browsing on the internet for a great price and without any hidden costs.
"The 5 Day Pass is not only a great price plan for the festive season, it’s a great addition to the existing portfolio of web’n’walk price plans such as the £1 per day pass.”