Technically it should just work. Isn't that a Verizon phone? All Verizon phones are unlocked from the beginning.
Only their world phones.
The ATIV SE is unlocked from the get-go, but be warned that while the basics will work, MMS, tethering might not. And the SE is tied to VZW for updates, and the update future looks pretty bleak NGL.
A shame though, its a real nice piece of phone.
Nope, on official WP8.1.1 it still can't work with MMS and tethering.I know that the ATIV SE will work with any GSM carrier except LTE(different bands), MMS(settings locked) and Internet Sharing(setting locked) with WP8. I have no problem with LTE and Internet sharing not working, just MMS. But now with the new official WP8.1.1 update, I wonder if the users of this device can add a new access point for MMS successfully and if they were able to sent and receive pictures/group texts.