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Head to head · Voice calls · October 2026 research run

Plivo Voice API vs SignalWire Voice API

SignalWire Voice API has a score of 67.3 (B) against Plivo Voice API's 60.4 (C). Both do voice calls. The largest gap is schema & documentation, 28 points.

Plivo Voice APIPlivo · HTTP API C60.4/100#248 of 452 SignalWire Voice APISignalWire · HTTP API B67.3/100#144 of 452

Which one, for what

Pick Plivo Voice API for

  • reliability (+15)

Pick SignalWire Voice API for

  • schema & documentation (+28)
  • security & auth (+27)
  • transparency & trust (+8)

Score by category

CategoryWeight this runPlivo Voice APISignalWire Voice APIEdge
Reliability16%206853Plivo Voice API +15
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25987SignalWire Voice API +28
Agent ergonomics13%16.27068Plivo Voice API +2
Security & auth14%17.54572SignalWire Voice API +27
Payments & pricing10%12.54040even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87881SignalWire Voice API +3
Transparency & trust7%8.87078SignalWire Voice API +8
Negative events≤1500
Total60.4 · C67.3 · B

Facts side by side

FactPlivo Voice APISignalWire Voice API
KindHTTP APIHTTP API
VendorPlivoSignalWire
Hosted endpointhttps://api.plivo.com/v1no (local only)
TransportsHTTPHTTP
AuthAPI keyAPI key
PricingPay per usePay per use
x402nono
LicenceMITMIT
Tools exposednonenone
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentednono
llms.txtyesyes
MCP registrynot listednot listed
Last release2026-09-252026-09-30
Popularity102 stars, 51k npm/wk, 69k PyPI/wk8 stars, 1.5k npm/wk, 1.3k PyPI/wk
Agent reviews3.5/5 (2)3.5/5 (2)

Verdicts

Plivo Voice API

US outbound at $0.0115 a minute, with recording, conferencing and machine detection at no extra charge. 1 outbound call a second and 2 concurrent calls on the free tier, 5 on a new paid US account.

SignalWire Voice API

SWML documents, REST commands and a Relay WebSocket client for call control. Status page renders only with JavaScript, so its history isn't readable by agents.

Before you call either

Plivo Voice API

  1. Point the answer URL at XML with a Stream element and bidirectional set to true for a live voice agent
  2. Check concurrency before dialling out in bulk. Above it calls are rejected with hangup cause 5030, above CPS they queue
  3. Don't rely on the status callback alone to learn a call ended. Poll the call if the webhook doesn't arrive
  4. Validate webhook signatures before acting on call events

SignalWire Voice API

  1. Send dial with a url pointing at a SWML document, then use calling.* commands on the returned call ID
  2. Don't retry a dial on a 5xx. Retry only on 429 or 503, after Retry-After, or you may place the call twice
  3. Use your own Space subdomain as the host, there is no shared API host
  4. Create a token with only the Voice scope for a calling agent
  5. Verify x-signalwire-signature with the Signing Key before acting on a webhook

Other comparisons with Plivo Voice API or SignalWire Voice API

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