SIM Card Selection for GSM Gate Openers and Auto-Dialers


We get asked a lot ‘what SIM should I use’ and ‘will X-brand SIM work?’ with our Alpha GSM boards.  Well the simple answer is any apart from 3 mobile.

Our board is a quad band board (  In the UK and Europe (indeed most of the world) the ‘2G’ standard GSM frequencies are 900/1800MHz and established networks, such as Vodafone, O2, Orange all have the infrastructure to support these bands.  The reason ‘3 Mobile’ doesn’t work with this type of equipment is because they never invested in it and just went straight to the 3G frequency of 2100MHz thus limiting their compatibility to 3G only equipment.  ‘3’ is the only network which does not have a 900/1800MHz infrastructure.

In the Americas they had a slightly different set of frequencies at 850MHz and 1900MHz making older ‘dual band’ equipment incompatible with the rest of the world.  Quad band products like ours mean no matter where you are in the world you will be able to find a network to support our products.

The final word on frequencies is that the 4G network operates at 800MHz and 2600MHz and if an operator started up who only offered 4G compatibility they would also not work with traditional GSM gate openers and auto-dialers (and all but the very latest phones!).

Vodafone, O2, Orange and T-Mobile all own 2G network infrastructure and also the licenses to operate on these frequencies so any of these networks will be compatible with our products – even if they offer 3G services.  The board will select the 900/1800MHz frequency from the SIM card and find the network using one of these bands.

Then we have the MVNOs (Mobile Virtual Network Operators) that resell the major network’s products as their own.  These are companies like Virgin Media (T-Mobile), Talk-Mobile, Vectone (EE which is in turn T-mobile and Orange) and so on.  You can often find a better deal using these MVNOs than you can through the major networks directly.

There is one MVNO you should avoid and they are called ‘shebang’ – they exclusively use the Three Mobile 3G only network!

Up to now we have been recommending Vectone mobile simply because they provide good value and also offer a £1 per month contract with up to 50 minutes.  You can find this deal on their website at:

If you have any queries please get in touch.


4 thoughts on “SIM Card Selection for GSM Gate Openers and Auto-Dialers

  1. John green

    I want to power the autodial from a 12v yausa battery. (It will be in an allotment shed where there is no mains). How long could a 12v 7AH battery run the autodialer for? The battery will not be driving other kit and I don’t expect the unit to make many calls.

    1. adventcontrols Post author


      Current consumption at idle at 12v is 35mA. The average consumption is a little higher and I would budget 50mA.
      This would give a 7Ah battery a life of 140 hours. You really need a solar panel. This is something we are working on specifying and I will be doing a post shortly on this subject


      1. jgreenpenrith

        Hi Michael,
        I came to the same conclusion as you so I did fit a 10 watt solar panel and charge controller to feed the autodialer and the 7 ah, 12 volt battery. It works well but if there are several dull wet days the battery doesn’t get sufficient charge, so to ensure the autodialer does not fail because of a loss of power, I replace the battery with a spare. So far, no problems. I’m pleased with the setup. For information the costs are:
        2 x 12 volt 7 ah batteries. £22.82
        1 x charge controller £9
        1 x 10 watt 12 volt solar panel £16.98.

        Can I make a suggestion about the autodialer plastic housing. I feel that it would make installation easier if the housing cover was held with screws that were accessible from the front and not the back. As it is at the moment all cableing must be fitted then the cover screwed down before the unit can be attached to a wall. To me it makes sense to have the case mounted on the wall. Then fit the cables then fix the cover. This is a very small change that would have helped me and does not change the fact that you have a terrific unit. I have recommended it to a couple of my friends. Thanks
        John Green

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