I have a 640 phone that I have loved. A couple of days ago I updated from windows 8.l to Windows 10. Spent a couple of days trying to get used to Windows 10 and then suddenly I realized MMS were not working (not able to send or receive). I tried deleting and putting back my outlook account, resetting the phone, and nothing helped. Today I downgraded back to Windows 8.1 in hopes of fixing the problem. I still can;t send or receive MMS. I called my carrier, Airvoice, and they gave me their settings which I re-entered. Still not working. I have done hard and soft resets, but have not done a hard reset where I don't re-install what I have backed up from my phone.