Local DNS server running at North Blackburn Shopping Centre
Raspberry Pi3 running Pi-hole
Installations instructions here https://blog.cryptoaustralia.org.au/instructions-for-setting-up-pi-hole/
Currently got the ad blocker disabled and just using it to handle DNS, and it obviously contains the required local record.
Basically a new file needs to be created in /etc/dnsmasq.d alongside the default file /etc/dnsmasq.d 01-pihole.conf
Called it 02-nbscpihole.conf and the following line was added
address=/nbsc.3cx.com.au/192.168.15.10
Then restarted dns and from another machine pinged nbsc.3cx.com.au and the 3CX phone server replied