Tmobile give webnwalk with the n900

i had to call them up and they changed it free of charge to webnwalk plus which has all ports open.

hope that helps...

solved all my issues straight away took 5-10 minutes on the phone just ask that your data package is changed to webnwalk plus as its a smartphone seen similar issues on the t-mobile forums they will know exactly why this is needed when you call.

hope that helps.