Encryption in transit protects data while it is moving between parties over a network, so that anyone intercepting the traffic sees unreadable ciphertext rather than clinical content. In a telemedicine stack this means two distinct mechanisms working together: TLS 1.2 or higher for API calls and signaling traffic, and DTLS-SRTP for the real-time WebRTC media (the actual audio and video of the consultation). They are not interchangeable — one secures the control plane, the other secures the live stream.
In practice, encryption in transit is mandatory for any path that carries Protected Health Information (PHI), and that includes paths a team often forgets: internal service-to-service hops inside your own cloud, webhooks to third parties, message queues, and log shipping. "It's inside our VPC, so it's fine" is not an argument that survives a HIPAA risk analysis, because perimeter trust is not a substitute for transport security. The Security Rule's transmission-security requirement looks at the data's whole journey, not just the public edge.
For a product team the discipline is end-to-end verification: trace every leg that PHI travels and confirm each one is encrypted, because the system is only as strong as its weakest hop. The classic pitfall is a beautifully hardened video channel sitting next to an unencrypted internal webhook, a plaintext database replication link, or analytics events sent over HTTP — any one of which is a finding on its own. Treat encryption-in-transit as a property of the entire data-flow diagram, audited regularly, not a setting you switch on once at the front door.
