Nokia Lumia 640 LTE RM-1073 (Cyan) - GSM Unlocked - International Version No Warranty DOES THIS DEVICE NEED A SIM CARD: Yes it does Being that this device is GSM unlocked it will work on any GSM Network with a Micro size SIM Card (3FF) The sim card does not come included and you will need to contact your Network Provider to acquire your complimentary Sim card (Free from most Carriers with activating of an account). WHAT NETWORK FREQUENCIES ARE SUPPORTED BY THIS DEVICE: Well the Short answer is 12 Bands, LTE Bands 1/3/7/8/20. 3G UMTS 850/900/2100. 2G 850/900/1800/1900 Which give it the ability to roam on LTE in many foreign countries, including all of Europe and much of Asia HOW LONG CAN I EXPECT THE BATTERY TO LAST ME: Well the battery has 2500mAh which in a Usage time frame means 2 solid hours of streaming at 4G LTE speeds or 1200 Minutes of Talking as well it has a Standby time of up to 840 hours before you need to recharge the battery WHAT DOES UNLOCKED REALLY MEAN: Unlocked devices are compatible with GSM carriers the kinds that Use SIM Cards for Service like AT&T and T-Mobile as well as with GSM SIM cards (e.g. H20, Straight Talk, and select prepaid carriers) Unlocked Devices will not work with CDMA Carriers the kinds that dont use sim cards for service like Sprint, Verizon, Boost or Virgin NOW TELL ME A LITTLE MORE ABOUT THIS PIECE OF HARDWARE: Well essentially your buying a little computer with a Mobile version of a full-fledged Computer processor a Qualcomm Snapdragon 400 MSM8926 (28nm) to be exact this CPU processor runs at 1.2Ghz Quad-Core ARM Cortex-A7 as well it is GPU graphical controller Qualcomm Adreno 305 at 400Mhz it comes with 1GB LPDDR2 RAM Memory and internal storage of 8GB (3GB user available) External Expandable to 128GB