that answer depends on which Breeze APIs you utilize and what types of endpoints you are working with (H.323, DCP, SIP).
AES talks exclusively to Communication Manager on the 'upstream' side (to invoke call control services). Communication Manager may then send messages through Session Manager to communicate with SIP endpoints. Communication Manager has the responsibility of communicating with H.323 or DCP endpoints that 'register' with it. The pathway to a remote endpoint may utilize SIP trunking through Session Manager, or other forms of trunking to reach remote Communication Managers.
Breeze APIs may initiate SIP call traffic, or may utilize APIs from other Avaya products (e.g AES) to initiate call activity.
Does that help or hurt?