Why does NFC sometimes stop ?

NFC works via a chip in the phone communicating with a chip in the receiving device, such as a speaker or payment terminal, to transfer data. It doesn’t usemuch power at all and works wirelessly so, when it works, it’s a great feature. However, lots of people report problems with NFC and that is generally due to the battery or phone case. If your phone says it supports NFC, but it has never worked, it could be because the chip is embedded in the back cover and that has been replaced at some point. This is the situation for phones such as the Samsung Galaxy Note 2. If it only works intermittently, are you swapping your batteries around? The Samsung Galaxy S3, for example, has the NFC chip in the battery, so if could lose NFC capability. The case could prove to be an issue if it ismade of a conductive material, such as metal. A standard plastic case shouldn’t affect the transmission at all. Check where the NFC chip in your phone is stored and make sure you aren’t occasionally removing it from the phone and losing the NFC capability.