I am having a VERY similar issue. Ive had my phone for years and on the same network with the same sim card. Suddenly it started saying invalid sim card. My service seems ok, but people can't hear me that well.
So I just bought a Samsung Galaxy S7 from some chick and I checked the phone and it seem to be ok, and I went home and put my sim card in it and it says invalid sim card I go on multiple websites to check the IMEI and it is unlocked but it wont work with the sim card I put in it (Cricket wireless) idk what to do
Jose707, if you have an unlocked Sprint phone, Sprint makes no guaranty that will work on another carrier's network. Whether another carrier will accept and activate a device is subject to that carrier's policies and capabilities. Details can be found here. I'd like to check the status of this phone, please send me Private Message including the MIED of this device. Click on my name and select "send a message".