Voice Quality API

Measure the network path quality to a voice/VoIP destination and get an estimated MOS (1–5) — live, from an API. Built for AI voice agents. Available as REST and as an MCP tool, paid per call via x402 (USDC on Base).

🌐 Live: voice-quality.com · REST api.voice-quality.com · MCP mcp.voice-quality.com

Try it

curl https://api.voice-quality.com/health          # {"status":"ok"}

curl -s https://api.voice-quality.com/v1/voice-quality \
  -H 'content-type: application/json' \
  -d '{ "target": "your-voice-endpoint.example", "target_port": 10000, "codec": "G711" }'

You get an estimated MOS + live RTT / jitter / packet loss. Point it at an endpoint that answers media — your own voice infra, or a tiny reflector you run (probe-agent/cmd/reflector). 20 free/day; beyond that it's pay-per-call via x402 (no account needed).

{
  "request_id": "vq_2ibc6qqq",
  "target": "your-voice-endpoint.example",
  "codec": "G711",
  "measured_at": "2026-07-01T10:15:13.795Z",
  "summary": { "mos_estimate": 4.38, "mos_class": "excellent", "r_factor": 91.8 },
  "by_probe": [ /* per-probe metrics + R-factor + MOS */ ],
  "methodology": {
    "model": "ITU-T G.107 E-model",
    "confidence": "estimate",
    "assumptions": ["owd = rtt/2 (symmetric path)", "adaptive jitter buffer = 2x jitter"]
  },
  "credits_used": 0
}

Related MCP server: Keel

Why it exists

Free network-measurement platforms (Globalping, RIPE Atlas) measure ping/traceroute/DNS/HTTP — they do not measure RTP media quality or estimate MOS. The tools that do (Cyara, Spearline) are enterprise sales motions. This fills the gap: voice path quality as a clean, self-serve, agent-native API — check it before you route a call, or monitor the path to your voice endpoints.

Trustworthy by design

• Honest metric. An objective G.107 E-model estimate from measured network metrics — never sold as a perceptual (PESQ/POLQA) score. Every response carries methodology.confidence: "estimate" and its assumptions.

• Verified constants. The codec Ie/Bpl values are verified against ITU-T G.113 (09/2024), App. I, Table I.4 — rows matched to the probe profile (no PLC, no VAD/DTX). Not "representative"; cited.

• SSRF-guarded. ~36.7% of public MCP servers ship SSRF issues — this one blocks internal/private targets by default (orchestrator and probe), plus a per-target allowlist and rate limit.

• Hardened. TLS/mTLS on the probe channel, non-root containers, pnpm audit clean, structured machine-readable errors, Idempotency-Key, Prometheus /metrics, per-identity API keys.

Pricing

Agent-native (MCP + x402)

One MCP tool, measure_voice_quality. The server wraps the REST API and pays x402 transparently from a configured wallet once the free tier is exhausted — no human in the loop.

{
  "mcpServers": {
    "voice-quality": {
      "url": "https://mcp.voice-quality.com/",
      "env": { "MCP_CLIENT_PRIVATE_KEY": "0x…" }   // optional; only for paid calls
    }
  }
}

Architecture

[AI agent / dev] ──(HTTP + x402 / MCP)──► [Orchestrator] ──► [E-model (G.107): R → MOS]
                                              └──► [regional probe] ──(emulated UDP/RTP)──► target

Self-host

cp .env.example .env                 # fill in values
docker compose up --build -d         # orchestrator + MCP + probe + reflector + landing
curl localhost:8080/health

Full deploy (public HTTPS via Caddy or Cloudflare Tunnel, regional probes with mTLS): docs/deploy.md. Going to production (mainnet x402, codec verification, registries): docs/go-live.md.

Docs

Methodology · OpenAPI · Deploy · Go-live · Discovery & registries

The MOS is an objective estimate from network conditions, not a guarantee of call quality. Maintained actively.