I have no understanding of OpenWRT at all so I'm just going by what I've got from various post in various forum.
All I know is that there is a GUI provided by LUCI to enable simple configuration.
I have an issue that when connection using SIP my connection drops after 30min. I want my instance of OpenWRT to stay connected to a SIP (voip) connection in definitely.
in the GUI ican add a local command to be executed post the boot. my attempt was as above but I believe in need to add something like:
/etc/config/session-timers=refuse or /etc/rc.local/session-timers=refuse to prevent the connection dropping.
It appears you are using firmware that is not from the official OpenWrt project.
When using forks/offshoots/vendor-specific builds that are "based on OpenWrt", there may be many differences compared to the official versions (hosted by OpenWrt.org). Some of these customizations may fundamentally change the way that OpenWrt works. You might need help from people with specific/specialized knowledge about the firmware you are using, so it is possible that advice you get here may not be useful.
Ask for help from the maintainer(s) or user community of the specific firmware that you are using.
Provide the source code for the firmware so that users on this forum can understand how your firmware works (OpenWrt forum users are volunteers, so somebody might look at the code if they have time and are interested in your issue).
If you believe that this specific issue is common to generic/official OpenWrt and/or the maintainers of your build have indicated as such, please feel free to clarify.
It's not really useful, as you're not running OpenWrt - evidenced by the fact your firmware version says "RangeXD WiBE 4G 4.0.3-rc2". I would suggest following @trendy's advice:
I was unable to find your device listed
By default, there's no SIP settings needed in most routers
I am not experiencing the issue on official OpenWrt versions 18-22