We see you're using an older browser that we no longer support

[VirtualLarry]

I got that message on Tmobile's "my.t-mobile.com" site, when I logged in. I'm using Waterfox 18.01 64-bit.

I would expect that message if I were using IE6 or IE7. Not a fairly up-to-date Firefox variant.

WTF?

 

[ViRGE]

To point out the obvious, you can't really compare IE and Firefox versions. Firefox version numbers may as well be the number of the latest security update; the only two versions of Firefox anyone is going to support is the latest version of mainline Firefox, and Firefox ESR.

To that end, Firefox 18 would actually be fairly old. That's 5 versions and god knows how many exploits back. I would assume their site knows what the latest version of Firefox is, and doesn't accept connections from out of date versions with known security flaws.