# How to Configure Things Group to Work Only With IMEI range (TAC)?
1\. Login to the Monogoto portal and go to ***Things Groups.***
2\. When Things Groups list opens, please find a Things group that you would like to configure to work only with specific device IMEI range and press on edit button.
3\. When Thing Group editing window opens, please press on button **Lock Master**.
4\. You should see a row called **IMEI prefix** appear. In this row please enter the device IMEI range, also known as a TAC.
5\. Please enter your IMEI device manufacturer range (TAC) in order to restrict Things inside this Thing Group to work only with devices from our entered IMEI range (TAC).
6\. In order to save our settings, please scroll down to the end of the page and press on button **SAVE & CLOSE**.
That’s all – the configuration has been completed.
Now that we have configured a Master IMEI functionality, when a device with a different IMEI range will try to use a Thing from our Things Group, the device will be denied the access to use the SIM card services.\
In below picture you can see Thing Menu example Event, showing denied use of data services, for a device that has a different IMEI range than we have configured in Master IMEI settings.
{% hint style="info" %}
[For more information about IMEI you can read this article
](https://en.wikipedia.org/wiki/International_Mobile_Equipment_Identity)[For more information about TAC you can read this article](https://en.wikipedia.org/wiki/Type_Allocation_Code)
{% endhint %}
{% embed url="" %}
How to Configure Things Group to Work Only With IMEI range (TAC)
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