Ahmad which application are you talking about ?
Neverthless, i had a MTC on my N900 and everything was working pretty well, don't worry.

I just have to mention that WAP connection might be a bit slow to sync email client for example or sometimes to do some other tasks as launching skype, but it's good for e-buddy web version, surfing and other stuff...

For any further help, please do not hestitate to ask.