Android 5.1 Operation System. Phone size: 165.5* 84.8*8.5mm. (L*W*H).</br>4 core dual Standby dual SIM card slots. Work with postpaid card. 3G - 850/2100 2G -850/900/1800/1900. US compatibility Nationwide on all GSM Networks including AT&T T-Mobile Cricket MetroPCS Straight Talk Pure Talk USA and others. Will not work with CDMA Carriers like Sprint Verizon Boost or Virgin.</br>Multi-function. G-sensor Bluetooth GPS Wifi Personal Hotspot MP3 player Mp4 player Gallery Sound Recorder Videos FM Radio Torch Google Search Gmail Play store etc.</br>Dual camera. Back camera is 5.0MP with flash light; Front camera is 2.0MP.</br>How to install SIM card? http://v.youku.com/v_show/id_XMTQyMjcxNjUxNg==.html</br></br>Product Description</br></br><b>Note:</b><br><br> - Pls make sure your card is postpaid card. Check with your carrier / provider before purchasing this item.<br> - Unlocked world GSM phone. 3G - 850/2100 2G -850/900/1800/1900. Compatible with at&t T-Mobile Straight Talk Simple Mobile and other GSM networks.<br> - Unlocked cell phones will not work with CDMA Carriers like Sprint?? Verizon?? Boost or Virgi