Step 1.) Upgrade to Debian 11 first
The process to go to Debian 12 is not as smooth as 11, when trying to upgrade from Debian 10. In fact, it doesn't work directly, so you'll first need to follow this guide to update to Debian 11, reboot and come back here if successful.
Step 2.) Update sources.list
Update your /etc/apt/sources.list like this:
deb http://........
Downloading and compiling from source to get the latest version of Asterisk is really simple with this guide.
apt install gcc make g++ libedit-dev uuid-dev libjansson-dev apt install libxml2-dev sqlite3 libsqlite3-dev
wget http://downloads.asterisk.org/pub/telephony/asterisk/asterisk-16-current.tar.gz
tar -zxvf asterisk-16-current.tar.gz
cd asterisk-16.6.2/
./configure
If you get this error change y........
This function and others may not work with the stock PHPinstall on Centos/CPanel: Fatal error: Call to > undefined function imagecreatefromjpeg()
Even with libjpeg-devel installed it won't work because PHP was not compiled with jpeg support, so we have to do the dirty work ourselves :)
Here is the command/yum's I did to install missing libraries for PHP that configure will complain about (yes it is a one by one process).
yum install bzip2-........