He told the club's website: "I was fortunate enough to play in the Champions League and Uefa Cup with Newcastle United.
"However, the difficult experiences I've had because of someone's opinion will make me appreciate this even more.
"I played against the likes of Podolski, Klose and Schweinsteiger about a year ago with the Republic of Ireland.
"I did say when I wasn't playing regularly enough for Portsmouth, the longer it continued I would be the loser in terms of playing for my country.
"That proved to be the case and I accepted it to a certain extent.
"But that isn't the case and I'd like to think that I have deserved the call-up after being exiled for the last 12 months."