Handset users milking T-Mobile’s $5.99 data plan might find a shock the next time they look to use 3rd party software to get full access to the web. Ports are being blocked on handsets to encourage heavy data users to switch (away from T-Mobile of course) to either the $20 or $30 unlimited data packages they offer. The reasoning is that the $5.99 plan is for light usage.

Maybe all the Vista users are huddled in Starbucks using up the bandwidth? (See CrunchGear’s post on Vista users getting FREE T-Mobile wireless access) Who knows, but with JD Powers constantly giving T-Mobile high marks for customer service, when you call in and complain, even with their inferior network (compared to Sprint), more than likely they’ll sweet talk you into the upgrade. So be careful.