Viewsonic Pocket PC, Sandisk WiFi & Starbucks?

I have a Viewsonic V37 PocketPC with PPC 2002, a SanDisk WiFi card and
an account with T-Mobile. I can connect with the PPC to my home and
office wireless routers, but not with my T-Mobile account at
Starbucks. I actually get an IP address and all the connections, but
it won't bring up the T-Mobile login screen or go past the router. I
can ping the router, but no farther. So far T-Mobile doesn't have an
answer.

Any ideas?

Thanks,
Jay Shilstone