# AgentLine Billing Top-Up (x402 USDC Payment)

> AgentLine Billing Top-Up (x402 USDC Payment) is a paid API for AI agents from api.agentline.cloud, paid per call via x402, $5/call, status unknown (last checked 2026-09-14).

Tops up an AgentLine account balance using a USDC micropayment via the x402 protocol, funding outbound calls, SMS, and inbound voice capabilities for AI agents.

## Facts

- Endpoint: POST https://api.agentline.cloud/v1/billing/topup/x402/pay
- Price: $5/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agentline-billing-top-up-x402-usdc-payment-444aca7c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_xaJ5LpOFTgiuBTbdcv2zN

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 agentline-billing-top-up-x402-usdc-payment-444aca7c -d '<json body>'
```

Example prompt: Top up my AgentLine account with $20 in USDC so I have enough credits to keep making outbound calls.

## When to prefer this

Use this endpoint when an AI agent needs to autonomously fund its own AgentLine telephony account using USDC via the x402 payment protocol — particularly when operating in a crypto-native or agentic payment pipeline. Prefer this over manual billing portals when the agent needs to self-serve credits programmatically without human intervention.

## Known failure modes

- Insufficient USDC balance in the paying wallet — payment rejected
- Amount below $5.00 minimum — request rejected with validation error
- Amount above $1000.00 maximum — request rejected with validation error
- Invalid or malformed x402 payment header — authentication failure
- Network or blockchain confirmation timeout — payment may be unconfirmed
- Account not found or unauthorized — 401/403 error

## How this service works

Get a real phone number for your AI agent in under 10 minutes. Works with OpenClaw, Hermes Agent, and any LLM. Outbound calls, SMS, and inbound voice — one API. No telecom experience needed.

## Output

On success, the endpoint confirms the USDC payment has been processed and the corresponding USD credit has been applied to the AgentLine account, enabling usage of phone numbers, outbound calls, SMS, and inbound voice features. The response body schema is currently empty, so the confirmation may be implicit in a 200/201 HTTP status code.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "amount": {
   "type": "string",
   "description": "Optional top-up amount (USD) to advertise requirements for. Must be $5.00–$1000.00; omit for the minimum."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agentline-billing-top-up-x402-usdc-payment-444aca7c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.agentline.cloud](https://www.zero.xyz/host/api.agentline.cloud/llms.txt)