I got my iPhone giving me some trouble,I was using a carrier and now I want to change to another one but when I put the sim card of the new carrier my iphone goes into Emergency Call only and when I remove it it goes back to homescreen.What can I do to fix this please? Help would be really appreciated.
Your phone is locked to the carrier you were using before. Search the forums for unlock options. There are a few different ways depending on which carrier you're on and what OS version and baseband you're using.