Im very confused on how to do this from google cloud platform. Would you have any Idea how? Sorry, I'm not experienced in this!OK well the good news is that there is a template in 3CX - although these will be EOL with the system soon: https://www.3cx.com/sip-phones/
Bad news is that you need to create a VPN tunnel from the cloud and use DHCP option 66 or directly put the provisioning link into each phone: https://www.3cx.com/sip-phones/dhcp-option-66/
How many phones do you have ? personally I think it would be best to get some cost effective supported phones and use the SBC or STUN:
https://www.3cx.com/sip-phones/
https://www.3cx.com/docs/3cx-tunnel-session-border-controller/
If you want to set those phones up to Google you will need a VPN connection:
https://cloud.google.com/vpn/docs/how-to
Founded in 2005, when VoIP was an emerging technology, 3CX has gone on to establish itself as a global leader in business communications.