Separate availability claims
An edge can remain reachable while its application tier, location store or media relay has failed. Define health evidence for each service. A successful SIP probe does not establish that calls can be authorized, bridged and heard. Track request rate, registration population, active dialogs and media traffic separately. Registration storms after network recovery can stress a different part of the platform from steady-state calls.
Understand what topology hiding changes
Topology-hiding mechanisms can alter what routing information is exposed across a signaling boundary. They do not replace authentication, tenant permissions or transport security. They can also create state or mapping dependencies that matter during node failure. If the platform controls a separate media relay, document its allocation, control access and cleanup. The signaling server's high availability does not automatically make an active relay session recoverable on another machine.
Exercise controlled failures
Test edge restart, application-node loss, database interruption and relay loss independently. Observe existing calls as well as new calls, and verify that recovery does not replay unintended operations or leak stale bindings. Keep a concise operational contract: which calls survive, which fail clearly, how endpoints reconnect and what an administrator must do. Prefer those measured outcomes over an unqualified highly available label. Use the same call identifiers and timestamps across edge, PBX and media evidence so failures can be reconstructed.
Sources & applicability
Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.
Examples require adaptation to your topology. No live PBX or hardware testing is claimed.