To make up the Avaya Aura Core, three essential links or relationships must be established. First, there needs to be a trust relationship between Avaya Aura System Manager (SMGR) and Avaya Aura Session Manager (SM), as this trust allows them to communicate and manage sessions. Second, creating a CM managed element in Avaya Aura System Manager (SMGR) is necessary for comprehensive management of Avaya Aura Communication Manager (CM). Lastly, a SIP Trunk between Avaya Aura Session Manager (SM) and Avaya Aura Communication Manager (CM) is essential for facilitating SIP signaling and communication. These three elements are crucial to ensuring proper integration and operation of the Avaya Aura Core.