How to use the Android MCP SMS Server in OpenAI Codex
This guide explains how to connect the Ozeki Android SMS Gateway MCP server to OpenAI Codex, enabling the AI assistant to send SMS messages directly from your Android phone. By following this tutorial, you will learn how to install the Ozeki Android SMS Gateway app, enable its built-in MCP server, register the MCP endpoint in OpenAI Codex, and verify that everything is working by sending a test message.
Solution: How to send SMS from OpenAI Codex
OpenAI Codex is connected to the Ozeki Android SMS MCP Server through the MCP protocol, where Codex is the MCP client and the Android phone is the MCP server. The Android phone is connected to the SMS service provider through a wireless mobile network connection. When an SMS is sent, it first travels from Codex to the Android phone through the MCP protocol, and the Android phone forwards it to the SMS service provider, which delivers it to the recipient's mobile phone.
What is OpenAI Codex?
OpenAI Codex is a terminal-based AI coding agent developed by OpenAI that allows developers to interact with AI models directly from the command line. It can read and write files, execute commands, and call external tools through MCP servers, making it a powerful assistant for automating development workflows.
What is an Android SMS MCP Server?
An Android SMS MCP Server is a Model Context Protocol server that runs directly on an Android smartphone and exposes SMS functionality — such as sending text messages and querying SIM subscriptions — as structured tools that any MCP-compatible AI client can call. Once installed and configured, the AI client can send real SMS messages through the phone's SIM card to any phone number, with a single tool call.
Download Ozeki Android SMS Gateway
To use this solution you need to install the Android app on your Android phone.
Download the android app: Android SMS Gateway
https://android-sms-gateway.com/p_51-download-android-sms-gateway.html
Steps to follow
You will need OpenAI Codex installed on your system.
- Install Ozeki Android SMS Gateway
- Enable MCP SMS Server
- OpenAI Codex SMS MCP Server Config
- Add the SMS MCP Server config to OpenAI Codex
- Send a test SMS
- Check the SMS in the SMS Gateway logs
Step 1 - Install Ozeki Android SMS Gateway
For a full tutorial on installing the Ozeki Android SMS Gateway, check out our How to install Android SMS Client and Enable Ozeki SMS Client permissions guides.
Before you can use the MCP SMS Server, you need to install the Ozeki SMS Client on your Android device. The app will serve as the local SMS gateway that OpenAI Codex connects to over your Wi-Fi network. Make sure both devices are on the same local network, as this is required for the HTTP connection to work.
Step 2 - Enable MCP SMS Server
For a full tutorial on enabling the MCP server in the Android app, check out our Android MCP SMS Server configuration guide.
Open the Ozeki SMS Client app on your Android device and tap the MCP tab in the bottom navigation bar. Tap the toggle switch to start the MCP server and grant any permission requests that appear, including access to SMS messages. The toggle will switch from "Stopped" to "Running" and the API endpoint URL will appear below. Copy this URL, as you will need it when configuring OpenAI Codex in the next step.
Step 3 - OpenAI Codex SMS MCP Server Config
# Replace {address} with your Ozeki Android SMS Gateway address
codex mcp add ozeki-sms-mcp --url http://{address}:9531/mcp
# Run the following command inside Codex to verify the connection
/mcp
Example prompt
Send an SMS to +36301234567, the message should be "Hello from Codex".
Step 4 - Add the SMS MCP Server config to OpenAI Codex
The following video shows how to add the Android SMS MCP server to OpenAI Codex step-by-step. It covers registering the MCP server using the command line, launching Codex, and verifying the connection.
Open a terminal window by searching for Terminal in the Start menu (Figure 1).
Run the following command to register the Ozeki Android SMS MCP server in OpenAI Codex.
Replace {address} with the IP address shown in the Ozeki SMS Client app
on your Android device (Figure 2).
codex mcp add ozeki-sms-mcp --url http://{address}:9531/mcp
Launch OpenAI Codex from the terminal. It will load the registered MCP servers, making their tools available for the session (Figure 3).
codex
Run the /mcp command inside Codex to list all connected MCP servers and
verify that ozeki-sms-mcp appears with a connected status. If the server does
not appear, check that the MCP service is still running on your Android device and
that the URL is correct (Figure 4).
/mcp
Step 5 - Send a test SMS
The following video shows how to send an SMS message from OpenAI Codex using the Ozeki Android SMS MCP server step-by-step.
Type a plain language instruction in the prompt asking the AI to send an SMS to a specific phone number. OpenAI Codex will call the Send SMS tool and process the request (Figure 5).
Send an SMS to +36301234567, the message should be "Hello from Codex".
OpenAI Codex may prompt you to allow the tool use before proceeding. This is a security confirmation to ensure you are aware that an external tool is being called on your behalf. Confirm the action to allow the AI to send the SMS (Figure 6).
You will see the result of the Send SMS tool call in the terminal. A successful response confirms that the message has been passed to the Android gateway and queued for delivery (Figure 7).
Step 6 - Check the SMS in the SMS Gateway logs
The following video shows how to check the gateway logs in the Ozeki SMS Client app step-by-step. This allows you to confirm that the SMS request from OpenAI Codex was received and processed successfully by the Android gateway.
Open the Ozeki SMS Client app on your Android device and navigate to the Settings tab in the bottom navigation bar to access the application settings. Tap the Log option to view the request and response history (Figure 8).
Select the MCP tab to show only MCP-related activity. Here you will see the incoming tool call requests from OpenAI Codex and the responses sent back, allowing you to confirm that the SMS was dispatched successfully (Figure 9).
Conclusion
You have successfully configured the Ozeki Android SMS Gateway MCP server with OpenAI Codex. Your Android device is now acting as a local SMS gateway that it can communicate with over your local network, enabling text messages to be sent to any phone number using plain language prompts. All SMS traffic is routed through your Android device's mobile connection, with no cloud messaging API or third-party service required.