TURN (Traversal Using Relays around NAT) is the relay of last resort in a WebRTC connection. When firewalls or a symmetric NAT prevent two devices from reaching each other directly, both sides instead send their media to a shared TURN server, which forwards it between them. This rescues the meaningful fraction of calls — often cited as roughly 10 to 20 percent, and notably higher on locked-down corporate and hospital networks — that would otherwise simply fail to connect. The cost is that relayed media takes a longer path, adding latency, and that every relayed byte is real bandwidth your TURN infrastructure pays for, scaling directly with usage.
For a telemedicine product team, TURN is both a reliability backstop and a recurring cost line that must be budgeted, not discovered. Hospital networks are notorious for aggressive egress filtering, so a clinical product that skimps on TURN capacity will see a steady trickle of consults that never connect — precisely the failures that erode clinician trust.
The compliance implication is decisive: because PHI-bearing audio and video physically transit the TURN server when it is in use, your TURN infrastructure sits inside the HIPAA compliance boundary. If a vendor hosts it, that vendor must sign a Business Associate Agreement (BAA), and the relay must meet your transmission-security obligations under the Security Rule (45 CFR §164.312). The common mistake is treating TURN as anonymous network plumbing and routing clinical media through an out-of-scope public relay.
The handbook · 7 volumes
Fora Soft Video Engineering Handbook
TURN relays media when firewalls block a direct path, and in hospital networks that can be a large share of calls and of your bandwidth bill. Our seven volumes cover the whole video stack; for TURN start with Volume 3: WebRTC, real-time media and the economics of delivery. Volume 2 covers NAT, TCP vs UDP and congestion control; Volume 7 covers cost per stream-hour. Written by Nikolay Sapunov, CEO at Fora Soft.
TURN relay costs growing as more consults run through hospital firewalls?
We will measure how many of your calls relay, right-size TURN regions and ports, and give you a plan with connection-rate and cost targets. 250+ video products shipped since 2005.
