How do I send a mobile text message to Finland from the USA?

I'm a little confused because all the other international numbers I have texted work fine, but for some reason I cannot send anything to Finland. The number series I have looks like this: +358 (x)xx xxx xxxx Does that look right for a Finnish number? What's weird is that in looking for help in my T. Mobile guide, they mention that I can send texts to any "standard ten digit mobile number." Obviously the above number is more than ten digits if you count the country code of 358. Am I supposed to use a different format? Any ideas would be appreciated.