Searching for an office SIP intercom solution

Hello, I’ve been tasked with finding an intercom solution for a medium sized office building. Ideally what I need it to do is have two intercoms on both sides of a locked door be able to communicate with each other, as well as paging a phone group using our PBX system when no one is available at the door. Some of the products I’ve found are the Fanvil i10/i10V/i10D mini intercom systems, but I’m not sure if it’s possible to make two of those communicate with each other. I have no experience in this realm so any advice or suggestions are sincerely appreciated. Thank you very much