The M20 is a complete Quad-band GSM/GPRS solution in a B2B connector type which can be embedded in customer application, offering the highest reliability and robustness. 
Featuring an industry-standard interface, the M20 delivers GSM/GPRS  850/900/1800/1900MHz   performance  for voice, SMS, data, and fax in a small form factor with extremely low power consumption. With a tiny configuration of 35mm x 32.5mm x 2.95mm, M20 can fit into almost all the  M2M  applications,  including  VTS,  Smart  Metering, Wireless POS, Security, etc.  

General features
Quad-Band         850/900/1800/1900MHz
GPRS multi-slot class        12/10/8
GPRS mobile station        Class B
Compliant to GSM phase  Class 4
2/2+                            (2W @850/ 900 MHz)
                                   Class 1
                                   (1W @1800/1900MHz)
Supply voltage range      3.4~4.5 V    4.0V nominal
Low power consumption 1.1mA @ DRX=5
                                   0.7mA @ DRX=9
Operation temperature   -45 °C to +85 °C
                                   35mm × 32.5mm × 2.95mm
Dimensions                   (incl. B2B connector:3.1mm)
Weight                        Approx 6g
Control via AT commands (GSM 07.07, 07.05 and other enhanced AT Commands)
SIM application toolkit

Specifications for fax
Group 3, class 1

Specifications for data
GPRS class 12              max. 85.6 kbps (uplink & downlink)
PBCCH support
Coding schemes           CS 1, 2, 3, 4
CSD                           up to 14.4 kbps
USSD
Non transparent mode
Protocols                   PPP
                               TCP/UDP
                               HTTP
                               FTP
                               MMS

Specifications for SMS via GSM / GPRS
Point-to-point MO and MT
SMS cell broadcast
Text and PDU mode

Specifications for voice
Speech codec modes          Half Rate (HR)
                                       Full Rate (FR)
                                       Enhanced Full Rate (EFR)
                                       AMR Half Rate
                                       AMR Full Rate
Echo arithmetic                 Echo Cancellation
                                      Echo Suppression
                                      Noise Reduction
Hands-free operation

Interfaces
Hirose 50-pin B2B connector
Power supply
External SIM                    3V/1.8V
Analog audio interfaces     Two channels
PCM Interface                 ( optional)
Serial port and debug port
Antenna connector and 
solder pad
Charge interfac

Drivers
MUX Drive

Compatibility
AT cellular command interface