I purchased the Samsung Galaxy J700/D a few weeks ago, I have had nothing but trouble with it. I only used the phone a few days, it started to act up, first, it froze lots, then, when I tapped the screen, it did not seem to respond until I did it a few times, then, it went super fast and turned itself off. Next, it would not receive Wi-Fi signals consistently, it is very sporadic. It is better with "Data" but even then, not too good. Today, I noticed I can not make calls from it as the reception is awful, it sounds like I am talking to robots, I cannot hear a word the other party is saying. My signal strength, no matter where I am is zero bars, so, I can not get reception at times at even the most powerful Wi-Fi hot spots.
I have tried everything, uninstalled programs, re-installed, turned the unit off and on, you name it, I have done it; it just keeps getting worse and worse, however, once in a great while, it will work fine for an hour or so, then bang, it starts to shut down or act up again.
I ordered it from Supero, it came from Hong Kong, I am wondering if it is a dud, the entire box, booklet, and keyboard was in oriental writing. I had to change it all over to English. I have written the company I purchased it from, but so far, they have not been very helpful. My Samsung Galaxy j5 works so much better, the only reason I wanted the J7 was due to more gigabyte room. I am sorry I did now. I certainly do NOT recommend this phone.