2) It can connect with ordinary telephone set, PBX , VOIP Gateway, Billing meter etc. ;

3) Dialing tone frequency:450hz;

4) Employ Industrial module [Sim300( Tri-band 900/1800/1900Mhz),M10(Quadband 850/900/1800/1900Mhz) or Q2403A(900/1800MHZ), to make;

5) Can adjust dial interval from 0.5sec to 9 secs by setting up from telephone set;                                         

6) Can adjust voice volume by setting up from telephone set;                              

7) SIM card supported (1.8V, 3V);
8) Caller ID display;
9) DTMF Dialing;
10) Bell signal;
11) Polarity reversal;
12) The RJ-11 socket which connect the phone or billing system for metering purpose;
13) Antenna socket (SMA);
14) IP Presetting;
15) Working status and Signal Strength by LED indicator;                                                 

16) IMEI Change (optional).

17) back up Li-ion battery( Optional) 7.2V 1300mAh.standby 24hrs,talking time: 2.5hrs.

Technical Specifications
Air interface standard: GSM850/1900Mhz,900/1,800Mhz phase 2+ full band
Frequency ranges:
A) GSM 850                                   GSM 1900:
I) Transmission: 869.2 ~ 893.8MHz      I) Transmission: 1, 930 ~ 1, 990MHz
Ii) Reception: 824.2 ~ 848.2MHz        Ii) Reception: 1, 850 ~ 1, 910MHz
B) GSM 900:                                  GSM 1800:
I) Transmission: 890 ~ 915MHz          I) Transmission: 1, 710 ~ 1, 785MHz             
Ii) Reception: 935 ~ 960MHz              Ii) Reception: 1, 805 ~ 1, 880MHz
Phone interface: supply RJ-11 Phone Interface
Hanging voltage: 45V
Picking off voltage: 30mA / 41mA
Dialing tone Frequency: 450Hz
Antenna interface: Antenna amplifying>2.5d