Main features
1. GSM 850 / 900 / 1800 / 1900MHz
2. Connecting metering box for payphone use
3. User-friendly installation; Plug & play
4. 2-phone connection
5. LED indicators for signal strength, status and power
6. SIM card locking and network locking
7. Reverse polarity signal support
8. Dtmf and pulse dialing
9. Emergency battery back-up
10. SMS (optional)
11. USB connector for PC connection (optional)
12. GPRS data transmission (optinal)