... lock card,lock terminal 2)support polar-reverse,12 or 16KHz pulse signal 3)support GPRS 8 ... Caller ID.4,Support secondary dial.5,Lock card, lock terminal.6,Send polarity reversal signal ... pulse for billing meter while connection is also compatible.8,Support GPRS . (Optional)9,Rechargeable battery, ... ~240 input7,DTMF Receive: > -23dB insure receiving.8,DTMF Receive sensitivity: 99.99%9,Insertion loss: ...