Thanks to the OP! I'd been putting off talking to ATT about some kind of contract renewal incentive and/or shopping other carriers, but this deal fit the bill perfectly. Two 6820 replacements for our T616s arrived today. I was seriously considering keeping the T616s and ebaying these, but the 6820s are SO much better at dealing with dodgy signal strength (common in my neighborhood) that I'm a happy convert.
For anyone considering a 6820, btw, my take on the phone is that it is outstanding for signal/voice/text (especially if you plan to use it for email-length text--the keyboard is fantastic); the physical design and quality/size of the screen, however, are mediocre and a definite step down from the T616. The camera is about the same as the T616, which is to say it's at best a toy, though the fact that it takes postage-stamp size video makes it a slightly more fun toy.
Anyway, hot deal and big thanks to the OP.