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I'd like to build a prototype of simplest possible GSM device - a simple modem with SIM holder, capable of logging on to the SIM's provider network and nothing else. It's meant to be used as a GSM localizing beacon in larger application. It's meant to be as small, as simple and as cheap as possible. Being crude or rough doesn't matter. I'm aware of >50$ GSM modules/modems, but they are too big and too pricey, and I'm looking for a better solution. I'm also wondering if the cheapest way is actually through the disassembly of an old mobile phone? I can get one for about $10 (or even for free from some junkyard) - the only problem with them is that they have a lot of unnecessary components and board space that's difficult to remove without damaging the GSM module.

Also, is it possible to craft such a device with some simple parts/engineering samples?

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  • \$\begingroup\$ Arduino and GSM shield (or reworked single board solution based on the same)? \$\endgroup\$ – Majenko Nov 3 '14 at 12:09
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    \$\begingroup\$ I'm not sure of your end goal but you mention a larger application so if it's just an initial prototype look at some Huawei products like the MG323-B. They'll be well under $10 in volume and looks like you can get them for not much more in one off qtys. \$\endgroup\$ – PeterJ Nov 3 '14 at 12:17
  • \$\begingroup\$ @PeterJ Hm. With shipping, I'd have to pay about $30 for one - and I can buy a used mobile phone for about 5-10$, I've edited the question. \$\endgroup\$ – user20088 Nov 3 '14 at 12:20
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    \$\begingroup\$ Worth reading: bunniestudios.com/blog/?page_id=3107 I think if you only want a single unit for the lowest possible cost, then building around a phone is the way to go. You won't be able to cut down the board area. \$\endgroup\$ – pjc50 Nov 3 '14 at 13:48
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Proprietary phones will not allow you to customize at all. But if all you need is to put in a SIM and log on, then I recommend to use an actual phone without even disassembling it.

Before you start reverse engineering a proprietary system, you are probably better off spending the extra money.

Shelling out over $100, I have had good results with the Arduino GSM Shield.

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    \$\begingroup\$ Frankly, I disagree; both modding and customizing phones with custom firmware or by using developer tools for given chipset is quite simple, at least for the most common & older ones. The same goes with chipping the board - it's more diffucult and the mileage may vary, but it's certainly possible and doable with some prior experience. Sending GSM modem commands can be achieved quite easily, as well as e.g. reusing phone's displays for microcontroller applications etc. Also, I've clearly stated that I'm aware of >50$ GSM modules/modems, but (...) I'm looking for a better solution \$\endgroup\$ – user20088 Apr 22 '15 at 22:07
  • \$\begingroup\$ Sorry to have no better advice for you at this point. You asked the question quite some time ago. Did you find an answer yourself? \$\endgroup\$ – Hauke Holtkamp Apr 27 '15 at 15:25
  • \$\begingroup\$ I used a junk-quality phone (severly damaged display) my friend was about to throw away, it did the trick for me. \$\endgroup\$ – user20088 Apr 27 '15 at 15:32
  • \$\begingroup\$ Great, then my recommendation wasn't so far off after all. :) \$\endgroup\$ – Hauke Holtkamp Apr 27 '15 at 15:34
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After a bit of searching (and various experiments with dismantling used phones), M590E got to be the module of choice for me; it's available in bulk quantities from different vendors worldwide, with Chinese vendor prices as low as $1 a piece (SIM card holder, passives & crappy antenna included :). It's a simple GSM modem capable of logging in to the network and sending AT commands & text messages, and works better than expected for something of this price range.

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