I was using this with Docomo and OCN Mobile. I mostly used it for the TikTok app. It's a micro SIM, so please use an adapter if you have a nano SIM card. The battery is a compatible replacement. It can charge to 100%. If you don't use it with mobile data off, it can last for several days. If you watch videos, it will run out of battery in a few hours. Use it at home for emails, music, camera, watching videos, etc. Batteries are still available for purchase. ① Known defects: The power button is missing. You can turn it on by touching the metal contacts inside with something like rolled-up aluminum foil. It takes a little practice, so I only use it about once a month for restarts. The bottom microphone is defective. Use the top microphone for hands-free calls, or use a headset. The back panel is cracked. Please see the photos. ② Functionality confirmed: Wi-Fi, Bluetooth, and LTE work. SD card works. The click feel of the active button in the upper left is not good, but it works. Volume buttons work. The three buttons at the bottom of the screen also work. The camera also works. The screen crack is 2-3 cm in the lower left corner, but it's on the black frame, so it's not noticeable. No sign of spreading. No impact on operation. The earphone jack was rusty, so I polished it. If it's not working well, try plugging and unplugging the plug. It's a robust product. Also, the Wi-Fi sensitivity is good, and it's easy to use even if your house is large and the signal is weak. I will properly reset the data before shipping. Capacity...16GB Carrier purchased from...docomo Defective functions...Yes Capacity...16GB Smartphone color...Camo Green