Signals and Authority

What SOSUS Taught Me About Sessions

Early in my career I worked inside the Sound Surveillance System, better known as SOSUS.

SOSUS was designed to detect and track submarines across vast stretches of ocean. The system combined multiple sources of information: fixed hydrophone arrays anchored to the seabed, aircraft dropping sonobuoys into the water, and different watch teams rotating through the monitoring stations.

Signals came and went constantly. One array might pick up a faint acoustic trace, then lose it. Another array hundreds of miles away might detect the same contact hours later. Aircraft could deploy sonobuoys that temporarily added new listening points into the system.

From the perspective of the sensors, the situation was messy and fluid. Signals appeared, disappeared, and reappeared across different instruments and locations.

But one thing did not change.

The contact designation.

Once a submarine was identified as a contact, that designation persisted. It followed the contact across sensors, across time, across entire ocean basins. Every observation, every classification update, every routing and reporting action referenced that same identity.

The sensors maintained the signal paths. The watch teams maintained the contact authority. Those were two different responsibilities.

The hydrophone arrays and sonobuoys solved the problem of signal continuity. They kept acoustic information flowing. The prosecution team solved the problem of authority continuity. They maintained the single governing identity that bound all those signals together.

One could change constantly. The other had to remain stable.

That distinction matters. If the identity changes every time a sensor changes, the system fragments. Each new signal becomes a new object, and coordination collapses. By keeping the contact designation stable, the system allowed a distributed network of sensors to behave as one coherent tracking system.

The Same Pattern Appears in Modern Communications

Modern real-time communication systems are extremely good at maintaining connections. Protocols like SIP and WebRTC can keep media streams alive across network transitions, adjust codecs mid-session, and move traffic between servers without interrupting the flow of packets.

In other words, they solve the transport problem very well.

But transport continuity is not the same thing as interaction continuity.

When a call goes unanswered, the system typically terminates the call and hands the interaction off to a separate subsystem. Voicemail is one system. Notifications are another. Message storage is another. The appearance of continuity is created by coordinating several independent processes after the fact.

The transport worked. The authority layer never existed.

Data Plane and Control Plane

Network engineers have a name for this separation. The system that moves packets is the data plane. The system that decides what those packets represent, where they belong, and how they are governed is the control plane.

In SOSUS, the sensors maintained the data plane. The contact designation function maintained the control plane.

The same separation appears in modern distributed systems everywhere: routing protocols, container orchestration, service meshes.

But in real-time communications, one layer has been missing. The session has never had a true control plane.

The Missing Layer

Hermes-Echo and the broader SSOAR architecture apply the same separation to live interactions. Transport systems continue to do what they already do well: maintain signal paths and media streams. The session identifier becomes the governing authority.

Instead of terminating an interaction when conditions change, the system maintains the session identity while its internal state evolves. Media can be injected, policies evaluated, accessibility activated, and responses captured without destroying the interaction context.

Transport continuity keeps the signal alive. Session authority keeps the interaction coherent.

A Small Correction

Nothing about this idea required new mathematics or new network protocols. The pieces already existed. What was missing was the recognition that transport continuity and authority continuity are different architectural problems.

SOSUS solved that distinction decades ago in a different domain. Hermes-Echo simply applies the same insight to modern real-time communications.