... four handsets at most.10. Connecting external power adapter with rechargeable battery .11. Displaying date, time, week, battery status, ... dialed calls . Handset function: 1. 2.4 G digital wireless phone.2. Locking keypad.3. Calculating call duration.4. Adjusting ... which can be divided into sixteen category, including wireless telephone, GSM terminal, wireless network card, PBX related to GSM, CDMA, ...