Pre-Call Tests that Cut WebRTC Support Tickets Fast

Nothing tanks adoption like a user’s first call failing. A lightweight pre-call test catches device, permission, and network issues before a session starts—slashing “it doesn’t work” tickets and improving CSAT.

What a pre-call test should prove (in 60 seconds)

1. Devices work: mic, speakers, camera enumerate and switch cleanly. Try the browser’s own APIs first (see Media Capture spec) and a live device preview (sample: enumerate devices demo).
2. Permissions granted: request mic/cam after a user click; re-surface prompts clearly for blocked states (reference: Permissions API).
3. Network viable: ICE can gather server-reflexive/relay candidates; TURN is reachable; round-trip <150 ms and loss <2–3% for voice.
4. Media path stable: short loopback call (15–30 s) with jitter/loss counters visible.
5. System ready: echo cancellation on, output device selected, CPU headroom sane.

Minimal implementation plan

• Step 1 – Device check: enumerateDevices() → let users pick mic/speaker/cam; show live VU meter and preview.
• Step 2 – Permission flow: trigger getUserMedia() from a click; store errors (NotAllowedError, NotFoundError) with human hints.
• Step 3 – Network probe: create a transient RTCPeerConnection with your STUN/TURN set; render gathered candidate types and latency.
• Step 4 – Loopback: connect two local peer connections; play a test tone and short speech clip; collect stats.
• Step 5 – Gate the join button: only enable when all checks pass—or allow override with a warning.

What to log (and alert on)

Use RTCPeerConnection.getStats() (spec: W3C WebRTC-Stats) and store:

• jitter, packetsLost, roundTripTime, framesDropped, selected candidate pair type
• Browser/OS, input device IDs, sample rates, hardware AEC on/off
• A simple pass/fail badge for Permissions, Devices, Network, Loopback

Pass/fail thresholds that work in practice

• Voice only: latency ≤150 ms, jitter ≤20 ms, loss ≤3%, CPU <80% while sending.
• Video 720p: sustained throughput ≥1.5 Mbps, dropped frames ≤5%, no Chrome “frame drops due to media” alerts.
• ICE: at least srflx or relay; if relay-only, show a “restricted network” banner.

UX details that remove friction

• One-screen checklist with green ticks; everything is undoable (change mic/speaker/camera live).
• Plain-language errors: “Microphone blocked in browser settings—click the lock icon next to the address bar.”
• A tiny share-with-support button that copies diagnostics as a link or JSON blob.

Rollout checklist

• STUN/TURN health probes per region with alerting
• Localisation for permission hints
• Dark-mode friendly VU meters and captions
• Privacy note: diagnostics are ephemeral; no raw media stored
• Admin switch to require a passed test for new agents

Payoff you can measure

Teams that gate sessions behind a 30-second pre-call test report:

• 20–40% fewer “no audio/video” tickets
• Higher first-call success rate and shorter time-to-resolution
• Happier agents (less guesswork) and clearer vendor handoffs

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