I have an unlocked Android - a Samsung Galaxy Golden, actually (which does not have a forum/much information online in general), but have been scouring information about other Samsung Galaxies due to a lack of information about my rather rare model. I bought it unlocked, and connected it to AT&T. I changed the APN settings so that it connected to the AT&T 3G network (H+) but I can't get it to connect to the 4G LTE network. Here are the settings I am currently using (which allegedly connect Galaxies to the LTE network):
Name: ATT HSPA+
Proxy: <Leave in Blank>
Port: <Leave in Blank>
Username: <Leave in Blank>
Password: <Leave in Blank>
Server: <Leave in Blank>
MMS proxy: proxy.mobile.att.net
MMS port: 80
Authentication type: <Leave in Blank>
APN type: default,supl,mms,hipri
APN Protocol: default
The Galaxy Golden (E400 K/S and i9235) are 3G supported only model phones for all carrier bands outside the 1800/2600 spectrum, as in all those carriers but United States.
This is funny, because theoretically the hardware supports Quad Band 4G LTE, but samsung decided to lock it up and throw away the key. Maybe if enough people write them friendly letters asking to release new firmware that unlocks the 700/1700 spectrum your U.S. ATT/T-Mobile network uses, they will be half inclined to analyze their potential market share for these types of phones.
Why would they lock the phone with software if the hardware already supports such feature?? I don't know, and we may never see a Clamshell like these phones in the U.S. markets because samsung has a name brand to follow and that name is "iPhone Killer" not "Granny Helper"