Difference between SIM900 and SIM900A GSM modems

Since we are already very familiar with interfacing the SIM900 modem and have played around with the AT commands, the questions that come to our mind are listed below. I have tried to answer them after doing a bit web research.

  • “What extra does SIM900 give me compared to SIM900A?” :

SIM900 is a quad band modem being able to operate in 850,900,1800,1900 MHz bands  

SIM900A is a dual band GSM modem being able to operate only in 900,1800 MHz bands

& SIM900A can only be used in Asia, as it is region locked to Asian markets. 

  • “How compatible are these both modems?” :

SIM900 modem operates from 3.4V to 4.5V supply range.

SIM900A modem operates from 3.2V to 4.8V supply range. (Maximized operating range)

Same AT commands used for call/sms in SIM900 can be used with the SIM900A modem.

  • “Why should i use the SIM900A modem?”:

The answer for this question is based on the need/requirement of your project. If your project is using the GSM modem for world wide compliance then go ahead with the SIM900 modem as it can operate in all 4 GSM frequency bands. If your application is only going to be implemented only in India and uses simple SMS, Call and GPRS functionality then use SIM900A as it is lower in cost compared to SIM900. 

For students and hobbyists SIM900A is highly recommended. 

  • “What is the price difference?”:

SIM900 is available for purchase @ Rs. 1200 /-   (Available @ www.probots.co.in @ Rs.1200/- )

SIM900A is available for purchase @ Rs. 1100 /- (Available @ www.probots.co.in @ Rs.1100/-)

  • “Where else can i buy SIM900/SIM900A?”:

For where to purchase electronics parts  visit the link >> Where to buy electronics components in India?

Or you can also search for SIM900/SIM900A availablility – Here,


 Also see: 


Leave a Comment