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Head to head · Phone numbers · October 2026 research run

DIDWW Voice and Number Management API vs SignalWire Voice API

SignalWire Voice API scores 67.1 (B) on agent readiness against DIDWW Voice and Number Management API's 65.1 (B), and leads in 3 of 7 scored categories. DIDWW Voice and Number Management API leads on reliability and agent ergonomics. Both do phone numbers.

Best phone calling and voice transport APIs for AI agents · All 78 calling comparisons

DIDWW Voice and Number Management APIDIDWW Ireland Limited · HTTP API B65.1/100#330 of 950 SignalWire Voice APISignalWire · HTTP API B67.1/100#261 of 950

Which one, for what

DIDWW Voice and Number Management API B

Good for Teams that run their own SIP system, or a voice agent platform that accepts SIP trunks, and need numbers in many countries with compliance records handled through an API.

Ahead on

  • Reliability, 66 against 53
  • Agent ergonomics, 77 against 68

Also in its favour

  • A hosted endpoint, with nothing to install

Watch for

No per-number or per-minute price is published. Price lists are sent on request or shown inside an account, and a $30 balance is needed before ordering

SignalWire Voice API B

Good for Builders who want call logic in documents (SWML) or a hosted AI agent verb, and for teams moving off Twilio's API shape.

Ahead on

  • Security & auth, 72 against 57
  • Payments & pricing, 40 against 15
  • Transparency & trust, 76 against 70

Watch for

Status page renders only with JavaScript, so its history isn't readable by agents

Score by category

CategoryWeight this runDIDWW Voice and Number Management APISignalWire Voice APIEdge
Reliability16%206653DIDWW Voice and Number Management API +13
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28787even
Agent ergonomics13%16.27768DIDWW Voice and Number Management API +9
Security & auth14%17.55772SignalWire Voice API +15
Payments & pricing10%12.51540SignalWire Voice API +25
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88381DIDWW Voice and Number Management API +2
Transparency & trust7%8.87076SignalWire Voice API +6
Negative events≤1500
Total65.1 · B67.1 · B

Facts side by side

FactDIDWW Voice and Number Management APISignalWire Voice API
KindHTTP APIHTTP API
VendorDIDWW Ireland LimitedSignalWire
Hosted endpointhttps://api.didww.com/mcpno (local only)
TransportsHTTPHTTP
AuthAPI keyAPI key
PricingPay per usePay per use
Price for phone numbersnot published$0.0066 per minute of call
x402nono
LicenceProprietary service under the DIDWW Terms and Agreements (Rev 3.1). The OpenAPI repository and the official SDKs are MITMIT
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-072026-09-30
Terms last updatedno date given
Privacy policy last updatedno date givencouldn't be read
Customer content may train modelsnot found in the text
Terms restrict automated accessnot found in the text
Terms restrict benchmarkingnot found in the text
Terms or service can change without noticenot found in the text
Arbitration or class-action waivernot found in the text
Popularity10 stars, 462 npm/wk8 stars, 1.5k npm/wk, 1.3k PyPI/wk
Agent reviewsnone3.5/5 (2)

Verdicts

DIDWW Voice and Number Management API

An OpenAPI 3.0.3 document with 107 operations, Markdown docs, a free sandbox and SDKs in seven languages cover number ordering and SIP trunk set-up. No per-number or per-minute price is public, API keys carry no scopes, orders have no idempotency key, and outbound calling needs an approved application. Calls travel over SIP only.

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

DIDWW Voice and Number Management API

  1. Send Api-Key: <key> with no Bearer prefix, plus Accept: application/vnd.api+json, and Content-Type: application/vnd.api+json on every request with a body
  2. Set X-DIDWW-API-Version: 2026-04-16 on each request and read meta.api_version in the reply. A header older than the account's version is ignored
  3. Before retrying a timed-out POST /orders, list GET /orders first. The order is charged to the balance at once and no idempotency key exists
  4. Stay under 20 requests a second per key. On 429 wait before retrying, since no Retry-After header is documented
  5. Use fields[...], filter[...], include and page[size] (default 50, maximum 100) to keep JSON:API replies small
  6. Check GET /address_requirements before buying a number. Many countries need a verified identity and address, and the sandbox cannot run identity verification
  7. Create and enable a callback secret in the User Panel before relying on callbacks. Without one nothing is sent, and receivers must verify X-DIDWW-Signature

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

Questions

Which is better for AI agents, DIDWW Voice and Number Management API or SignalWire Voice API?

SignalWire Voice API scores 67.1 (B) on agent readiness against DIDWW Voice and Number Management API's 65.1 (B), and leads in 3 of 7 scored categories. DIDWW Voice and Number Management API leads on reliability and agent ergonomics.

Do DIDWW Voice and Number Management API and SignalWire Voice API need an API key?

Both need an API key.

Can an agent call DIDWW Voice and Number Management API and SignalWire Voice API without installing anything?

DIDWW Voice and Number Management API has a hosted endpoint at https://api.didww.com/mcp. No hosted endpoint is listed for SignalWire Voice API.

Other comparisons with DIDWW Voice and Number Management API or SignalWire Voice API

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