I am looking for a device that has an internet connection via a mobile sim. It allows owners of enabled telephone numbers to switch a relay by ringing the device sim.

The system will be used to allow the opening of a gate only to owners of authorized telephone numbers, who through a call to the system will activate the relay which will pilot the arm for opening.

The device must be able to register its IP address on dyndns in order to be accessible via url.

More precisely, the device must allow me remotely, via internet connection:

1) upload a list of telephone numbers to an archive;

2) enable / disable telephone numbers indicating whether they are always enabled or a date and time of enabling and disabling

3) have a log, downloadable remotely, of the various accesses with date and time

4) The relay must remain closed for a predefined time and then open automatically

  • 1
    What problem are you actually trying to solve? Edit the question to add more details about what this device would be used for
    – hardillb
    Jan 4, 2020 at 17:25
  • 1
    sounds like something that you will need to design and build yourself
    – jsotola
    Jan 4, 2020 at 19:26
  • 3
    why are you asking at multiple sites? ... arduino.stackexchange.com/questions/71477/…
    – jsotola
    Jan 4, 2020 at 19:44
  • I posted the request on multiple sites since I still don't know what the site that can offer me the solution can be
    – famedoro
    Jan 6, 2020 at 17:48

1 Answer 1


There seems to be several contradictions in what you are asking for here.

  • If it's turned on/off by ringing it, why does it need to be internet connected at all?
  • If it's internet connected why does calling the phone number control turning it on/off, when you could just send it a message via the internet connection.

Most Mobile data plans use Carrier Grade NAT which means that all devices get given a non internet routable IP address (RFC 1918) and then connections pass though a NAT gateway. You can get SIMs that offer routable addresses but these are intended for emergency fallback when Broadband lines go down or industrial applications and tend to only be available to businesses and cost a lot more.

There are ways round the GGNAT, that normally involve connecting out to known static location e.g. a VPN or a port forwarding application.

A simpler solution would be to use SMS to configure the device. Building something like this is relatively trivial with an micro controller and a GSM adapter.

Also what you are asking for is basically a remote detonator for a bomb, which probably explains why you can't find one to buy off the shelf.

  • 1
    The internet connection is necessary to configure the telephone numbers enabled for relay switching and to allow me to download the logs remotely. The relay must remain closed for a predefined time and then open automatically
    – famedoro
    Jan 4, 2020 at 16:52
  • 1
    That doesn't answer the question about why this all can't be done via the internet. I'm guessing this is a form of smart lock you are trying to build, so all I'll say is that faking caller ID is REALLY EASY
    – hardillb
    Jan 4, 2020 at 22:20

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