A few months ago I bought an unlocked Tmobile MDA on eBay. I slipped the SIM card out of my Motorola V505 and into the MDA and it immediately worked well as a phone on Suncom.
After a few settings changes, I was browsing the Internet with the Internet Explorer that comes with the Windows Mobile 5 system that the phone is supplied with. In fact using the Outlook, Word, Excel, IE, and Power Point Viewer is remarkably easy and similar to their desktop counterparts.
Excel has been very handy as a Grocery List. I also use it to store several xls files I created and emailed to the phone as attachments. Files can also be easily transferred and kept synced with the Active Sync application.
Active Sync is also used to setup scheduled sync of the Built in Outlook with an Outlook Exchange server. I have a free account setup on an Outlook Exchange account with mail2web.com. This works very well. I now have a calendar that is easily updated online from anywhere, including from my phone, and it is kept synced on both. In addition when I plug the phone into my home PC, it syncs that PC’s Outlook calendar.
In addition, it easily syncs with a Hotmail account I have, the pop email server at my home ISP. With the browser I am easily able to check Gmail, manage 28 Yahoo Groups I moderate, trade stocks on Scottrade, check the weather, my bank account, etc.
The fact that many web sites provide a version of themselves designed to be viewed on small screens is very nice also.
I highly recommend this phone. In fact, I recently bought another unlocked MDA for one of my daughters. She loves it also, and is finding all the installed applications to be very handy.