StablePhone
Have an AI voice agent phone a US or Canadian number and carry out a task. Each call settles $0.54 in USDC on Base over x402.
Per call
$0.54
Invoke this API
# Inspect the endpoint. curl does not complete x402 payment.curl --request POST 'https://x402phone.dev/api/call'
# Pay one request from a vapi-network wallet. Add --content-type and --body for the request input.vapi pay 'https://x402phone.dev/api/call' \ --method POST \ --expected-pay-to 0xD219dB8179Bb9C1899eF87f39eebA9D1070c6801 \ --max 0.10
call.pay {"url":"https://x402phone.dev/api/call","method":"POST","maxPriceUsd":"0.10","expectedPayTo":"0xD219dB8179Bb9C1899eF87f39eebA9D1070c6801"}Try it
https://x402phone.dev/api/callThis API does not describe its inputs. Add each input it needs as a name and a value.
Request preview
This is the exact URL and payload used for the unpaid price check.
- Request
- POST https://x402phone.dev/api/call
- Content type
- application/json
- Body
{}
The browser refuses to sign if the live quote exceeds this amount.
Response
Technical details
About this API
StablePhone, run by Merit Systems, places an AI phone call over x402. Send a +1 phone number and a task that tells the voice agent what to say; the call starts once the $0.54 USDC payment settles on Base and the response returns a call_id. Numbers on the Do-Not-Call list are refused. Only the paying wallet can read the transcript, through StablePhone's own status endpoint.
The browser checks the live x402 terms before every paid call. If CORS blocks a direct request, vAPI gives you the exact vapi-network handoff.
For agents
Prompt for AI
Paste this into any agent that can pay over x402. No API key needed.
I want to use the "StablePhone" API listed on vAPI Call.
Have an AI voice agent phone a US or Canadian number and carry out a task. Each call settles $0.54 in USDC on Base over x402.
Endpoint: POST https://x402phone.dev/api/call
Price: $0.54 per call, pay per use via x402 (USDC on Base). No API key required.
Input schema: (not published — pass the inputs the task requires)
What it does: Direct x402 AI phone call. Body: { "phone_number": "+1XXXXXXXXXX", "task": "what the agent should say" }.
Important notes — read before calling:
- The live 402 challenge is authoritative: trust its price, recipient, and terms over this prompt.
- vAPI has verified this listing.
Call the endpoint over x402 (for example with the vapi-network MCP `call.pay` tool) and return the result. I will provide the inputs next.Need a wallet your agent can spend from? Set up vapi-network