Support normal extension port. Specilized SIM card in case of misuse in mobile phones after decrypt. Support GSM virtual network. Phone book storing up to 100 phone numbers. Attached small keyboard to input more conveniently. Ringing even in off hook mode. 128*64 LCD with background light showing five lines of calling information, date and time. Support keyboard locking. User can set up to 10 barred calls. Support speed dialing by one key. Long-distance call locking (PSTN only). Support carrier locking. Automatically add IP access number ahead of long distance calls. GSM900/DCS1800MHz dual mode adaptation. Short messages. incoming caller ID. Receiving calls in hands free mode and hanging up automatically when finishing the call (GSM only) Restore history records of calls. Support up to 18 types of ring tones. Intelligent power management. Detecting the batteries to recharge or discharge automatically. Support management through both SMS and serial port. Using industrial wireless module. 850/1900mHZ frequency optional. Please visit our website for more products selection. contact email: