A DoorBird door intercom system can be integrated into a SIP installation in the following ways
DoorBird IP video door station with a SIP phone (peer-to-peer connection [P2P])
DoorBird IP video door station with PBX and one or more SIP phones (connection via PBX)
DoorBird IP video door station with PBX with telephone provider and one or more analog telephones and one or more SIP telephones (connection via PBX)