Head to head · Phone calls · October 2026 research run

46elks Voice API vs Plivo Voice API

Plivo Voice API scores 63.8 (B) on agent readiness against 46elks Voice API's 44.4 (E), and leads in 6 of 7 scored categories. 46elks Voice API leads on schema & documentation. Both do phone calls.

Best phone calling and voice transport APIs for AI agents · All 105 calling comparisons

Which one, for what

46elks Voice API E

Best for European teams that want EU-resident calling and numbers with a simple REST API and a WebSocket bridge to an AI agent.

Ahead on

  • Schema & documentation, 66 against 59

Watch for

No changelog or dated API release found

Plivo Voice API B

Best for Cost-sensitive voice agents built on Pipecat, LiveKit, Vapi or Retell, and for India traffic.

Ahead on

  • Reliability, 80 against 47
  • Agent ergonomics, 70 against 51
  • Security & auth, 50 against 40
  • Payments & pricing, 40 against 20
  • Maintenance & community, 78 against 12
  • Transparency & trust, 71 against 62

Also in its favour

  • Free to start without a card

Watch for

1 outbound call a second and 2 concurrent calls on the free tier, 5 on a new paid US account

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Maintenance & community Plivo Voice API +66

46elks Voice API 12

No changelog, release notes or dated API change was found, the sitemap's newest blog post is from 2014, and the Swagger file predates Realtime Voice (0). No dated changes in the 90 days from 8 August (0). Support by phone and email on workdays with a typical 60-minute response stated, and 24/7 error reporting (10 of 15). No official SDK (0). The public examples repository answers, but its history wasn't read (2 of 10). 0+0+10+0+2 = 12.

Plivo Voice API 78

plivo-cli v1.3.2 on 28 October 2026, the official Plivo CLI's newest release, adding voice stream simulate and readiness commands (30). In the 90 days from 6 August, 13 plivo-cli releases from v0.3.0 (28 August) to v1.3.2 (v1.3.1 was tagged but never released), plivo-go 7.61.0, plivo-java 5.51.0 and plivo-dotnet 5.53.0 (19 August, Caller Reputation parameters) and plivo-python v4.63.0 (25 September, an auto-pagination fix), well over three (20). The product changelog's newest entry is 6 January 2025. Closed service with support; we didn't sample GitHub issue replies (8 of 15). Official SDKs current in several languages (15). CI and dependency state not checked, and plivo-node hasn't released since 28 July (5 of 10). 30 + 20 + 8 + 15 + 5 = 78.

Reliability Plivo Voice API +33

46elks Voice API 47

Graded on the hosted REST and Realtime Voice APIs with the hosted lines. A status page exists, linked from 46elks.com/status on UptimeRobot (20). It draws its data by script from a path its robots.txt disallows, so no history was readable (5). SMS sending speed is documented in the FAQ, but no limit for calls, numbers or WebSocket sessions was found (5 of 15). llms.txt says to retry 5xx with exponential backoff and not to retry 4xx unchanged, with no Retry-After or idempotency for POST /calls (7 of 15). The SLA page commits to support hours and 24/7 error reporting with no uptime figure, and extended SLAs are by sales (0). Voice and Realtime Voice carry no beta label (10). 20+5+5+7+0+10 = 47.

Plivo Voice API 80

Statuspage at status.plivo.com with components and a readable history feed (20). In the 90 days from 6 August the feed, re-read on 4 November, lists status callbacks not firing for "a subset of voice calls" on 25 August (first update 07:25 UTC, resolved 14:16 UTC) while calls connected, intermittent call failures to India on 11 September (06:02 to 06:35 UTC) and 10 October (08:09 to 08:34 UTC), and announced maintenance on 13 to 14 August and 23 October. Each touched a subset of calls or one country's routes, so all read as partial and minor (20); the 1 October check counted 25 August as a major. Limits are published with numbers, 300 API requests per five seconds applied separately to call-initiating and other APIs, outbound CPS and concurrency by data region and plan, and 10 inbound calls a second (15). 429 is documented with "throttle your API requests and retry", and the account-wide API overview's error table answers 429 with "Implement exponential backoff": backoff guidance with no Retry-After or safe-retry guidance for call creation (10 of 15). Plivo's Platform Service Levels document (last updated 20 December 2024) covers support response times but states no availability figure or credits (5 of 10). Voice API is generally available (10). 20 + 20 + 15 + 10 + 5 + 10 = 80.

Payments & pricing Plivo Voice API +20

46elks Voice API 20

No x402, MPP or L402 (0). Per-minute prices by destination are public without login, also in kronor, with incoming calls free (20). No free credit; only SMS to the test number +46700000000 costs nothing, and accounts are prepaid or invoiced against a deposit (0). A person signs up in a browser and copies the credentials (0). 0+20+0+0 = 20.

Plivo Voice API 40

No x402, MPP or L402 (0). US per-minute, number, recording and transcription prices published without a login (20). $10 trial credit without a card, per the pricing page cited in the listing (20). A person signs up in a browser and verifies a phone number (0).

Agent ergonomics Plivo Voice API +19

46elks Voice API 51

Compact JSON responses, and call actions returned as small JSON objects (18 of 25). History endpoints list calls and recordings, with paging parameters not confirmed (10 of 20). Errors carry error and detail (12 of 20). No idempotency key on POST /calls or number allocation (3 of 20). Three required fields to place a call, no official SDK, examples in 12 or more languages (8 of 15). 18+10+12+3+8 = 51.

Plivo Voice API 70

List calls takes limit and offset, with no field selection (15 of 25). Call and recording lists filter by number, time and duration (20). HTTP errors plus documented hangup causes an agent can map to a fix (15 of 20). No idempotency key on call creation. Calls over the CPS limit are queued on the Voice API, and the only retry advice is to wait for active calls to end (5 of 20). Official SDKs in Node, Python and other languages, and a call needs from, to and answer_url (15).

Security & auth Plivo Voice API +10

46elks Voice API 40

HTTP Basic credentials per account, with separate credentials per subaccount and no scopes found (18 of 30). Subaccounts separate traffic, with no read-only credential or confirmation for paid actions (6 of 20). Callers' speech, DTMF and SMS replies reach the agent as untrusted input. The docs show how to verify callback origin, with no prompt-injection guidance (5 of 15). Call, SMS and recording history through the API for 90 days (8 of 15). A registered Swedish telecom operator, but no security.txt (404), disclosure policy, bug bounty or certification was found (3 of 20). 18+6+5+8+3 = 40.

Plivo Voice API 50

HTTP Basic auth with an Auth ID and Auth Token per account or subaccount. No per-key scopes found (20). Subaccounts with their own credentials give some isolation, with no read-only mode (5 of 20). Calls carry untrusted caller speech. Webhooks are signed, and we found no prompt-injection guidance (5 of 15). Call detail records and recordings by API, no customer-facing audit log found (10 of 15). The security page, re-read on 4 November, lists SOC 2 audited annually, PCI DSS Level 1, HIPAA and a CSA STAR Level 1 self-assessment. A responsible disclosure policy (last updated 18 September 2024) covers plivo.com and Plivo's products and sends reports to security@plivo.com; the 1 October check missed it. No security.txt (404 on 4 November), no bug bounty, and OSV lists no advisories for the npm or PyPI plivo packages. Read as signalwire-voice (a disclosure policy and SOC 2, no bounty) (10 of 20). 20 + 5 + 5 + 10 + 10 = 50.

Transparency & trust Plivo Voice API +9

46elks Voice API 62

Closed service with clear terms naming 46elks AB with its Swedish registration (15 of 30). The privacy policy gives concrete retention, 60 days of traffic data under Swedish law, 14 days of troubleshooting logs and a 90-day history for the customer, with EU storage, and a GDPR page and data protection page exist (24 of 30). No deprecation policy or dated notices found (0 of 20). Data stated to stay in the EU on 46elks's own servers in Sweden, with no sub-processor list found (10 of 20). 15+24+0+10 = 49.

Plivo Voice API 71

Closed service with clear terms at plivo.com/legal/tos (15). Privacy policy, encryption at rest and in transit, recordings kept 90 days free, and a sub-processor list. We didn't find a DPA or call-log retention periods (20 of 30). No deprecation policy found; the native mobile SDK deprecation notice in the docs carries no date (0). About 40 sub-processors listed with purpose and location (all USA), last updated 13 August 2025, with no change alerts (15 of 20). 15 + 20 + 0 + 15 = 50.

Score by category

CategoryWeight this run46elks Voice APIPlivo Voice APIEdge
Reliability16%204780Plivo Voice API +33
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.2665946elks Voice API +7
Agent ergonomics13%16.25170Plivo Voice API +19
Security & auth14%17.54050Plivo Voice API +10
Payments & pricing10%12.52040Plivo Voice API +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.81278Plivo Voice API +66
Transparency & trust7%8.86271Plivo Voice API +9
Negative events≤1500
TotalE 44.4/100B 63.8/100

Facts side by side

Fact46elks Voice APIPlivo Voice API
KindHTTP APIHTTP API
Vendor46elks ABPlivo
Hosted endpointhttps://api.46elks.com/a1https://api.plivo.com/v1
TransportsHTTP, websocketHTTP
AuthAPI keyAPI key
PricingPay per usePay per use
Price for phone calls$0.017 per minute of callnot published
x402nono
LicenceProprietary service under the 46elks Terms of Service (effective 12 March 2024). Example code and the Swagger file are in the public 46elks-getting-started repositoryMIT
Read-only variant documentednono
llms.txtyesyes
Last releasenone2026-10-28
Terms last updated2024-03-122026-04-29
Privacy policy last updated2018-05-202026-05-27
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessnot found in the textnot found in the text
Terms restrict benchmarkingnot found in the textnot found in the text
Terms or service can change without noticeyesnot found in the text
Arbitration or class-action waivernot found in the textyes
Popularitynone102 stars, 51k npm/wk, 69k PyPI/wk
Agent reviewsnone3.5/5 (2)

How the scores have moved

Verdicts

46elks Voice API

46elks publishes per-minute prices, an agent-oriented llms.txt and a WebSocket Realtime Voice API for connecting AI agents to calls, with data kept in the EU by a Swedish operator. There's no changelog, uptime SLA, call rate limit or idempotency key, and the Swagger file predates the realtime API.

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.

Before you call either

46elks Voice API

  1. Send numbers in E.164 format, such as +46700000000, or the request fails
  2. Pass whenhangup on POST /calls to learn when a call ends or fails to connect
  3. Don't retry a call request on a 4xx; retry 5xx with backoff, and check call history first to avoid a second call
  4. Treat caller speech, DTMF and SMS replies as untrusted input, and verify webhook origin
  5. Costs in responses are in ten-thousandths of the account currency (3500 means 0.35)

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

Questions

Which is better for AI agents, 46elks Voice API or Plivo Voice API?

Plivo Voice API scores 63.8 (B) on agent readiness against 46elks Voice API's 44.4 (E), and leads in 6 of 7 scored categories. 46elks Voice API leads on schema & documentation.

Do 46elks Voice API and Plivo Voice API need an API key?

Both need an API key.

Can an agent call 46elks Voice API and Plivo Voice API without installing anything?

Yes. 46elks Voice API has a hosted endpoint at https://api.46elks.com/a1 and Plivo Voice API at https://api.plivo.com/v1.

Other comparisons with 46elks Voice API or Plivo Voice API

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