I also own a P280 using T-Mobile and haven't received such a letter (yet). However the P280 is very much an orphaned phone -- it was the first of the GPRS phones and Motorola decided to go in a different direction, with new software development. Leaving the P280 as an oddball. I've tried many times to replace it, but cannot find another phone with similar function -- specifically the antenna range! It has much better signal strength than any of the newer phones, making quite a difference in coverage area (and T-Mobile has spotty coverage in much of the US, making this more important than it should be). Unlike in Europe where everyplace is covered. I'm intending to keep my P280 for as many years as I can.

I did get a software download to my phone last week (very rare, these happen once or twice a year) but have no idea what it was. I did happen to have my phone's sim card replaced by T-Mobile a few months ago as it was an old format sim which became "incompatible" with their network at the last round of upgrades, and the store clerk claimed that he also "refreshed" the microcode in my phone at the same time. So it might be that you can go to a T-Mobile store (NOT a dealer!) and get this done. Perhaps the microcode refresh is the real requirement and they don't want to do this for free.