Functions: Charging automatic Low voltage shockproof protection technique Call Records Charging Rate and Number Segment Management Locked to specified operator, Cell lock, Interlock of phone and SIM/UIM card Features: Network management: The management system can exchange data with telephone set by sending message through message center or wireless modem, for instance, inquiring about/downloading telephone parameters, phone bill reporting, charging rate management, malfunction warning and report. Double LCD screen: It is user-friendly especially for wireless telephone users. Emergency battery backup，with a design of low electricity consumption Technical Specification Air Interface Standard GSM:900/1800MHZ CDMA :450/800/1900MHz GPRS GPRS multi-slot Class 10, Class B Operating Mode Phase Error