Hi all, Hopefully I'm not committing a faux pas by asking a question that gets asked a lot. I spent a couple of hours looking around the forum and didn't find anyone else asking exactly what I need to know, so... Is it possible to upgrade the Android OS on a mobile device and later downgrade it without rooting the handset? Specifically I'm curious about whether we can do this with a HTC Tattoo / Desire / Legend and a Sony Xperia X10, but also with Android devices in general. I ask because this is for testing purposes (not of the handsets, of other mobile apps and websites) and I'd like to be able to upgrade and downgrade the OS on each handset as is required for a test. I'd prefer to do this through a means other than rooting because of 1.) the time rooting seems to involve (I've never done it but reading over the process makes it sound a bit time-consuming?) and 2.) we'd like to make our handsets as representative of the 'average user' as possible, and I'd guess that most people don't root their phones. If anyone can offer any tips or point me in the right direction that would be really appreciated. Thanks for reading!