With special thanks to Josh Culp, we are pleased to provide an upgrade script for Incredible PBX 2020 that upgrades Asterisk 16 or 17 on CentOS 7 or 8 platforms to Asterisk 18. Any Asterisk 18 bugs should be reported to issues.asterisk.org.
tar zxvf upgrade-asterisk18rc1.tar.gz
rm -f upgrade-asterisk18rc1.tar.gz
sed -i 's|47|50|' /usr/local/sbin/pbxstatus