I used the SIM from her S4 in my S4 and it's working, verified. My wife has her SGH-I337 with Android 4.4.4 on AT&T getting the 'no SIM detected message' with a known new working SIM and a newly replaced SIM + microSD card reader installed. I do not blame any app, Google (Android), AT&T or Samsung for this but I do think that the last three players in this list need to put their heads together and find a fix as soon as possible. Just Google 'SIM card removed Unable to detect your SIM card' to learn the extent of this problem. Obviously I cannot prove what I think but I have trawled the web and have been provately investigating this problem for a few months now. My phone is now out of warranty so AT&T will not help other than providing a new SIM card. Even with only stock apps in Safe Mode, the fault never goes away. The fewer 3rd party apps it use (email, calendar, etc.) the fewer faults I have. I have re-booted my phone many times, I have run it in Safe Mode and I have re-flashed it back to 4.4.2. Android then tells the app there is a failure and Android then reports SIM unavailability. it has just suffered a micro-interruption and is in the process of just coming up or just going down AND any app needs connectivity, it may be that the SIM reports as not being available. If the network is in a state of flux i.e. This is a random event when regarded from a user standpoint. What I believe is happening is this, many apps need network connectivity from time to time.

I am almost certain this is not a SIM card contact problem. Now I have fixed tow thicknesses of clear Scotch office tape to the back of the SIM card. I have changed my SIM card and have reseated it several times. It really began to manifest itself under 4.4.2 and became really bad (3 - 10 times daily) under 4.4.4. I had this problem on my Samsung GS4 SHG-i337 very intermittently under 4.2.2. I believe this to be a problem between an app or a number of apps, Android and the AT&T network.

Samsung s4 sim card hack