PARTNER
AI phone call API for agents
Outbound AI voice calls, wallet-owned phone numbers and carrier lookups — pay per call in USDC via Circle Gateway.
Outbound conversational AI calls via Bland.ai, and dedicated US/CA phone numbers via Twilio. Numbers auto-register with Bland on purchase so they can be used as outbound caller-ID. Carrier and fraud lookups round it out. Every endpoint pay-per-use.
Number provisioning is currently limited to US and Canada. SMS is not offered — A2P 10DLC registration adds 1–4 week onboarding friction. Inbound (receiving calls) isn't enabled yet; this is outbound-only for now.
What Agents Use It For
Anywhere your agent needs to reach a human in real time — verification callbacks, appointment reminders, voice surveys, automated outbound — without standing up telephony infrastructure or signing carrier contracts.
Endpoints & Pricing
All endpoints are 402-gated. Send a request without payment to receive payment requirements, then re-send with a Circle Gateway signature attached. Settlement happens after the upstream Twilio or Bland call succeeds — failed upstream calls are not charged.
| Method | Endpoint | Price | Purpose |
|---|---|---|---|
| POST | /v1/voice/call | $0.54 | Outbound AI conversation call (Bland.ai). Defaults to 5 min, max 30 min. |
| GET | /v1/voice/call/{call_id} | free | Poll call status, duration, transcript, and recording URL. |
| POST | /v1/phone/numbers/buy | $5.00 | Provision a dedicated US/CA number, wallet-bound for 30 days. |
| POST | /v1/phone/numbers/renew | $5.00 | Extend the lease on a provisioned number by 30 days. |
| POST | /v1/phone/numbers/list | $0.001 | List active numbers owned by your wallet. |
| POST | /v1/phone/numbers/release | free | Release a provisioned number back to the Twilio pool. |
| POST | /v1/phone/lookup | $0.01 | Carrier identification + line type (landline, mobile, VoIP). |
| POST | /v1/phone/lookup/fraud | $0.05 | Lookup + fraud signals (SIM swap, call forwarding). |
How It Works
Behind the Scenes
Powers number search, purchase, lease management, release, and carrier + fraud lookups. We absorb Twilio's per-month carrier fee in the $5 number price.
twilio.comPowers the actual voice AI — STT, LLM, TTS, interruption detection, voicemail handling. Your Twilio numbers are imported into Bland on purchase so they can be used as outbound caller-ID (BYOT).
bland.aiAI phone calls for agents, question by question.
- What is the AI phone call API?
- POST /v1/voice/call places an outbound conversational AI call from a natural-language task prompt: the agent dials, speaks, listens and responds in real time. $0.54 per call, five minutes by default, thirty at most, with transcript and recording available by polling GET /v1/voice/call/{call_id} for free.
- How much does an outbound AI voice call cost?
- $0.54 per outbound call, paid in USDC through Circle Gateway. Numbers are $5.00 to buy and $5.00 to renew for 30 days, carrier lookup is $0.01, and lookup with fraud signals is $0.05. Every price is in the 402 before the call runs.
- Can an AI agent own a phone number?
- Yes. POST /v1/phone/numbers/buy provisions a dedicated US or Canadian number bound to your wallet for 30 days, and it is auto-imported into Bland on purchase so the agent can use it as caller ID on outbound calls. Renew for $5.00, release for free.
- How does this compare to using Twilio, Bland, Vapi or Retell directly?
- Those need a human to open an account, add a card, create an API key and manage a monthly bill. Here the calling wallet is the account: no signup, no key, and each call is priced and paid per request in USDC. Bland and Twilio are the carriers behind the endpoints — you get the same calls and numbers without holding a contract with either.
- What is the phone number lookup and fraud API for?
- POST /v1/phone/lookup returns the carrier and line type (landline, mobile, VoIP); /v1/phone/lookup/fraud adds SIM-swap and call-forwarding signals. Agents use it for KYC, anti-fraud checks and routing decisions before placing a call.
- How do I pay for AI voice calls with USDC?
- Deposit USDC once into Circle Gateway on any of 11 EVM chains, then the SDK signs each request off-chain. No per-call gas, no API key. Circle's facilitator verifies the signature before the call is placed.
- Which countries can the AI calling API dial, and which numbers can I buy?
- Numbers are provisioned in the United States and Canada. Outbound calls are placed by Bland.ai from those numbers or from the shared pool; check Bland's current destination coverage for international dialing.
- Does the AI phone agent give me a transcript and recording?
- Yes. GET /v1/voice/call/{call_id} is free and returns status, duration, the full transcript and a recording URL once the call completes.
Get Started
All you need is USDC pre-deposited at the Circle Gateway on any accepted chain (Polygon, Arbitrum, Optimism, Unichain, Avalanche, Sonic, Sei, WorldChain, HyperEVM, Ethereum, Arc). Hit any endpoint, get a 402, attach payment, get the response.