SIM900S which is compatible with the module-SIM300. This is a complete Dual-band GSM/GPRS module in a B2B type and designed with a very powerful single-chip processor integrating AMR926EJ-S core, allowing you to benefit from small dimensions and cost-effective solutions. The target market of SIM900S is China mainland and India.
SIM900S delivers GSM/GPRS 900/1800MHz performance for voice, SMS, Data, and Fax in a small form factor and with low power consumption. The leading features of SIM900S make it ideal for applications such as WLL applications and handheld devices.

General features
* Dual-Band 900/ 1800MHz
* GPRS multi-slot class 10/8
* GPRS mobile station class B
* Compliant to GSM phase 2/2+ 
Class 4 (2 W  900 MHz) 
Class 1 (1 W 1800MHz)
* Dimensions: 40*33*3 mm
* Weight: 7g
* Control via AT commands (GSM 07.07 ,07.05 and
SIMCOM enhanced AT Commands)
* SIM application toolkit
* Supply voltage range :3.2 ... 4.8V
* Low power consumption: 1.0mA(sleep mode)
* Operation temperature: -20  to +60

Specifications for Fax
* Group 3, class 1

Specifications for GPRS Data
* GPRS class 10: max. 85.6 kbps (downlink)
* PBCCH support
* Coding schemes CS 1, 2, 3, 4
* PPP-stack

Specifications for CSD Data
* CSD up to 14.4 kbps
* USSD
* Non transparent mode

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

Software features
* 0710 MUX protocol
* Embedded TCP/UDP protocol
* FTP/HTTP

Specifications for Voice
* Tricodec 
Half rate (HR) 
Full rate (FR) 
Enhanced Full rate (EFR)
* Hands-free operation
(Echo suppression)
* AMR 
Half rate (HR) 
Full rate (FR)

Interfaces
* 60 PIN Board-to-board connector
* Two analog audio interface
* RTC backup
* SPI interface
* UART interface
* SIM Interface
- Option1: SIM holder (to external SIM 3V/ 1.8V)
- Option2: Embeded SIM
* Keypad
* GPIO
* PWM
* ADC
* Antenna connector

Compatibility
* AT cellular command interface