# Palmyr Phone Call Speak

> Palmyr Phone Call Speak is a paid API for AI agents from palmyr.ai, paid per call via x402, $0.08/call, status unknown (last checked 2026-09-13).

Send text-to-speech audio into an active phone call identified by a call control ID, paying $0.08 USDC per call via x402 on Solana or Base.

## Facts

- Endpoint: POST https://palmyr.ai/phone/calls/%7BcallControlId%7D/speak
- Price: $0.08/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/palmyr-phone-call-speak-a3f943d9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fkIVxrQ6WLUokHkHDbX0j

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability palmyr-phone-call-speak-a3f943d9 -d '<json body>'
```

Example prompt: Say 'Your appointment is confirmed for tomorrow at 3pm. Thank you for calling.' into the active call with control ID abc-123-xyz right now.

## When to prefer this

Use this endpoint when you need to inject synthesized speech into a live, in-progress phone call and you have a valid callControlId. Ideal for AI agent telephony workflows where autonomous bots need to speak during calls, deliver dynamic messages mid-call, or run IVR-style interactions — and you are equipped to pay per-call in USDC via x402 on Solana or Base.

## Known failure modes

- Invalid or expired callControlId returns 404 or error — call may have ended
- Insufficient USDC payment or failed x402 payment flow returns 402 Payment Required
- Text content missing or malformed returns 400 Bad Request
- Call already terminated before speak action is processed
- Network latency causes speak action to arrive too late in call lifecycle

## How this service works

Autonomous infrastructure for AI agents — pay with USDC on Solana or Base via x402.

## Output

A confirmation that the text-to-speech audio was successfully injected into the active phone call identified by the callControlId, along with any status details about the speak action.

## Request schema (JSON Schema)

```json
{
 "properties": {
  "input": {
   "properties": {
    "body": {
     "type": "object",
     "additionalProperties": true
    }
   }
  },
  "output": {
   "properties": {
    "example": {
     "type": "object",
     "additionalProperties": true
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/palmyr-phone-call-speak-a3f943d9/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from palmyr.ai](https://www.zero.xyz/host/palmyr.ai/llms.txt)