GSM Guidance


I am working on a plethora of control circuits and various projects using the Arduino/ATMega family of chips and am looking to integrate some GSM functionality into my projects for now, and in the future, utilize the internet, etc. I have been searching for different GSM modules and found a variety but some seem to be rather expensive, others unavailable. I wanted to ask and see what everyone thinks in terms of a cost effective solution that works for simple calling/text messaging functionality, and then also on a separate note - internet capability. Open to any ideas and suggestions and I appreciate the ideas - Thanks.



There are many low-cost GSM/GPRS modules on the market these days. If you are concerned mainly with cost, the cheapest are based on the SIMCOM SIM900 module. There are several vendors but I am familiar with the ITEAD one.

At US$32, these are quite a bargain.

There are a few models based on the Quectel M10, including the official Arduino GSM Shield product. These are more expensive than the SIM900 based units, but the level of software support in libraries and such is a bit better.

Some things to consider when choosing a module might be:

  • cost
  • the type of baseband module and the sort of software support available for it; is there confirmed Arduino library support with the features you want?
  • antenna connection options -- built-in, FRL, SMA, RPSMA; is an antenna included?
  • power requirements -- most have an on-board regulator, most modules require and external power source -- ie: they can't just be run off a USB connection; is the regulator a high-efficiency switching one or an LDO linear?
  • form factor and mounting options -- some are "shield" form-factor that you may find convenient or inconvenient, depending; some lack mounting holes; does it have what you need?
  • Analogue call support electronics -- ie: microphone and headphone connections. Need them?
  • RTC power (is something I am worried about in particular) -- is there a provision for powering the RTC -- supercap or coin cell or even just the RTC supply broken out somewhere?


Thanks for the detailed reply it is very informative and helpful. I have looked at the SIM900 and Quectel M10 and they both definately seem of interest. I also have seen some various forums mentioning the SIM300, but cannot find any info on where to buy it. I was unable to load the link you provided for the 32 dollar SIM900 but It seemed like a more affordable solution.

Now on to the more important parts - Ideally I would love an antenna - on board or not, but it shouldnt need to be very elaborate.

Being that my programming skills are not great - I'd love to find something that has a good library, or at least a good way to send and receive text messages and calls, and gather simple information (time, date, etc) from the web. Do you think that leans me towards the Quectel M10's?

For power, efficiency is great but I am not opposed to something with an LDO either for now. I'd just love to get this implemented into my software sometime in the near future.

For now I will not need microphone/headphone but I could definately see the use for a mic in the future.

Any tips from here would be very helpful. Appreciate all the assistance.



I think the ITEAD web-site is actually broken at the mo. Here's their module on Robotshop:

It sounds like your main criterion is going to be minimizing software frustration and interfacing complications. Based on that, the Arduino GSM Shield is the low-risk option.

Maybe have a look at the SIM900 library --
and compare to the GSM Shield library --
and consider which looks the closest match to your needs.

It looks like they both should do about what I want, but the GSM shield with a little more ease and ability to branch out into new projects. I just stumbled across both of these and although shipping may take a while, it was a little bit more inexpensive.


Do you think these would be compatible with the SIM900 and the GSM shield, respectively? It seems so but I can't tell having never used them before.

Thanks again for all the guidance its helpful having someone point me in the right direction who knows what they're talking about!


The first one is pretty bare-bones -- it doesn't have a regulator or anything. It would be a headache to get that going IMO. The other ones looks fine. Although it resembles a shield form-factor, I don't think it is one.


I will check that one and the other two suggested out. Thanks again much appreciated!