Disallowing some users access to the relay on the GSM Dialer and Gate Opener

We had a user question which required a unusual solution so I thought this is ideal for the blog.  Quite crafty I’d say!


Another question for you. The relay can be activated with a call. Is there any way of setting the numbers that can do this. I don’t want all the text numbers to be able to use the relay. See I have set this up as a back up to a pager system. Should it fail I only want 3 numbers only to be able to set it off the relay. Thanks again for your time and help

GSM Switch

GSM Switch with Volt-Free Relay Output


I had to have a little think about this one. The easy answer is no. All numbers can operate the relay. What you can do though it add an extra digit to the end of the phone number you don’t want allowed. When the dialer searches the memory it looks at the last 8 digits of the number you gave it. If I did this with my number:

Actual: 07574163367

Given to dialer: 075741633670 (added a 0)

The dialer would get 07574163367 from the network but when it looks in its memory it will only see 41633670 which will not be a match so it will not allow the relay to be operated. However, when it sends messages or dials the number you have given it, it will add the extra 0 but the network will know this is too long and ignore it. Try the SIM in your mobile and see if it does actually call/send messages with the extra character. Mine does and I use an EE SIM.

So for those you want to access the relay put the number in correctly and for those you don’t add the character.


Advent Controls

GSM Dialer Link

GSM Gate Opener Link

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