Adding custom context

please kindly assist as i am still new to pbx.
I have a raspbx set up with 24 extensions having 3 extensions each on 1XX, 2XX…9XX.
I want only extensions in 1XX to be able to reach each other and same with the 2XX, 3XX to 8XX. but i want all extensions to be able to reach the 9XX and the 9XX able to call all extensions.
Please how do i go about it.
Thanks

This forum does not provide support for FreePBX. Use https://community.freepbx.org/

FreePBX uses the the term extension in a different way from Asterisk.

In Asterisk, you put the devices you want to be in in each tenant group into different contexts and you use a different dialplan context for the extensions they can call.

Thanks for your reply. It is running on asterisk 13 and i have created an extension_custom.conf but i get the eror message " chan_sip.c:26468 handle_request_invite: Call from ‘102’ (192.168.0.138:57898) to extension ‘100’ rejected because extension not found in context ‘users’. "

You need to take this to the FreePBX forum.

However, it looks like the device is matching sip;conf entry with the context users, not the one with whatever context you intend to use for callers who are limited to 1XX numbers.

Thanks for your response.