# AgentPhone Outbound Voice Call

> AgentPhone Outbound Voice Call is a paid API for AI agents from AgentPhone at mpp.orthogonal.com, paid per call via MPP, $0.1/call, status unknown (last checked 2026-10-11).

Initiates an outbound voice call from an AI agent's provisioned phone number, either autonomously (with a system prompt) or webhook-driven.

## Facts

- Endpoint: POST https://mpp.orthogonal.com/agentphone/v1/calls?utm_source=zero.xyz
- Price: $0.1/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Provider: AgentPhone
- Docs: https://api.agentphone.ai
- Website: https://api.agentphone.ai
- Tags: phone, voice, sms, calls, social
- Canonical page: https://www.zero.xyz/c/agentphone-outbound-voice-call-f924f2b6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_T4vh2Uh7OGu5C7rJ9oS0L

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 agentphone-outbound-voice-call-f924f2b6 -d '<json body>'
```

Example prompt: Call +1 (555) 867-5309 using my AgentPhone agent and have it introduce itself as 'Aria from Acme Support', ask the person if they received their order, and let the AI handle the conversation autonomously from there.

## When to prefer this

Use this endpoint when you need an AI agent to autonomously initiate and conduct a real voice phone call — especially when natural spoken conversation, real-time interaction, or human-sounding dialogue is required. Prefer this over SMS endpoints when the task requires back-and-forth dialogue, nuanced communication, or voice specifically. Choose the autonomous mode (with systemPrompt) for fully self-directed calls, or webhook mode for custom call-flow logic.

## Known failure modes

- Invalid or unprovisioned destination phone number — returns 400 with validation error
- Agent ID not found or unauthorized — returns 401/403
- No phone number provisioned for the agent — returns 422 with setup instructions
- Insufficient balance or payment failure — returns 402
- Destination number unreachable or call rejected — call status set to failed after attempt
- Missing required fields (e.g. destination number) — returns 400

## How this service works

Make an outbound voice call. Include systemPrompt for autonomous AI conversation, omit for webhook-driven mode.

## Output

Returns a call object with a call ID and status indicating the outbound call was initiated. On completion, may include transcript and recording details. The call proceeds in real-time either autonomously using the provided system prompt or routed through a developer webhook for custom logic.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agentphone-outbound-voice-call-f924f2b6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mpp.orthogonal.com](https://www.zero.xyz/host/mpp.orthogonal.com/llms.txt)