# Give your coding agents real phone numbers.

> Give Claude Code, Codex, Cursor and OpenCode a real US phone number, including real SIM lines, so they can sign in to your own app, read the code and text your product without asking you.

Your agent gets its own number. It presses Send code in your app, reads the code that arrives and types it in, without stopping to ask you to read your phone.

## Watch it get past the code.

1. **Mark the number.** Only a text that arrives after this counts.
2. **Send the code.** The agent presses Send code in your app, in the browser it controls.
3. **Read it and sign in.** It reads the code over MCP and types it in.

The same three steps work in a test, so the agent can leave behind a test that proves sign-in on every push.

## Set up in one command.

Install the skill, approve the connection in your browser, and name the number your agent should use. The skill uses MCP where your agent supports it, and the command line otherwise.

- **Claude Code**: `npx skills add https://www.phonekit.io --skill phonekit --agent claude-code --copy`
- **Codex**: `npx skills add https://www.phonekit.io --skill phonekit --agent codex --copy`
- **Cursor**: `npx skills add https://www.phonekit.io --skill phonekit --agent cursor --copy`
- **OpenCode**: `npx skills add https://www.phonekit.io --skill phonekit --agent opencode --copy`
- **Playwright**: `npm install @phonekit/sdk`
- **GitHub Actions**: `- run: npx phonekit@latest message mark --number ci-signin`

## What agents do with a number.

Anything your own app does over text. These are where most teams start.

1. **Sign in to your app**: Finish a sign-in, sign-up or phone-change flow without stopping for you.
2. **Text your product**: Send a message from one of your numbers and check what your product says back.
3. **Leave a test behind**: Turn what it just did into a test with its own number, for every push.

## Decide what each agent can read.

Share a number with an agent the way you share it with a teammate. Its connection reads only the numbers you choose, and you can take that access away at any time.

## The details.

- **Numbers**: US numbers. Standard is local VoIP; Mobile is a real SIM line on a mobile network. [VoIP or real SIM](https://www.phonekit.io/learn/voip-vs-real-sim)
- **Agents**: Claude Code, Codex, Cursor and OpenCode, plus any MCP client. [Setup guides](https://www.phonekit.io/integrations)
- **Ways in**: An agent skill, an MCP server, a CLI, a JS/TS SDK and an HTTP API. [Docs](https://www.phonekit.io/docs)
- **Messages**: The whole text of each message, with codes and links pulled out.
- **Waiting**: Only texts after the mark count. The wait ends at the deadline you set, up to an hour. [How marking works](https://www.phonekit.io/learn/one-number-per-test)
- **Sending**: Closed loop only, with per-number limits that keep the lines trusted. [Limits](https://www.phonekit.io/docs/api#sending)
- **Access**: Each connection reads only the numbers you give it. People sign in with passkeys. [Security](https://www.phonekit.io/security)
- **Setup**: One command per agent. Your workspace is ready usually within a day. [Quickstart](https://www.phonekit.io/docs/quickstart)
- **Price**: From $29 a month for four numbers, including a real SIM line. [Pricing](https://www.phonekit.io/pricing)

## Questions

### Which coding agents work with Phonekit?

Claude Code, Codex, Cursor and OpenCode have their own setup guides. Any agent that can use a skill, an MCP server or a command line can use Phonekit.

### Can the agent read any text, not just codes?

Yes. It reads the whole message: who sent it and what it says. Codes and links are pulled out for convenience, so an agent can follow an invite link or check your product's reply as easily as a code.

### How fast does the agent get the code?

As soon as the text reaches the number. How long that takes depends on the service that sends it. The agent waits up to the deadline you set and then reports that nothing arrived.

### Can the agent read a code from before it started?

No. It marks the number before it presses Send code, and only a text that arrives after the mark counts, so an old code never gets used.

### What can an agent see?

Only the numbers its connection or key has been given. It never sees the rest of the workspace, and you can remove its access at any time.

### Can the agent send texts?

Yes, inside a closed loop: your own numbers, your teammates' verified phones, anyone who texted the workspace in the last 30 days and up to five numbers you add, with per-number limits.

### Is this for signing up to other services?

No. Phonekit is for building, testing and running your own product, where you control the app that sends the text.

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Source: https://www.phonekit.io/agents