How to send SMS through SMPP from Claude Cowork
This guide explains how to connect Claude Cowork to Ozeki SMS Gateway's built in SMS MCP server, enabling the AI assistant to send and receive SMS messages through your own on-premises SMS gateway. You will learn how to install Ozeki SMS Gateway, create an MCP user account, generate an API key, register the MCP endpoint in Claude Cowork, and verify the setup by sending a test message.
Solution: How to send SMS from Claude Cowork
Claude Cowork connects to the SMPP SMS MCP Server through the MCP protocol, where Claude Cowork acts as the MCP client and Ozeki SMS Gateway acts as the MCP server. Ozeki SMS Gateway is installed on your local machine or server and connects to the SMS service provider over the internet using an SMPP client connection. When an SMS is sent, it first travels from Claude Cowork to the Ozeki SMS Gateway as an MCP tool call, and the gateway forwards it to the SMS service provider over SMPP, which delivers it to the recipient's mobile phone.
What is Claude Cowork?
Claude Cowork is a desktop productivity application developed by Anthropic that brings Claude AI directly to your Windows desktop. It allows you to automate file and task management workflows using plain language instructions, without requiring any coding knowledge. The application supports MCP servers, enabling it to be extended with external tools such as SMS messaging, database access, and more, making it a powerful automation platform for everyday computer tasks.
What is an SMPP SMS MCP Server?
An SMPP SMS MCP Server is a standardized software bridge that uses the Model Context Protocol to connect AI assistants (like Claude) to an SMS gateway system such as Ozeki SMS Gateway, which in turn delivers messages to the mobile network over an SMPP client connection. It exposes tools like "send_message" or "list_incomings" that an AI can autonomously call to perform real-world texting tasks without custom coding. This allows users to simply ask an AI to "send John a reminder text" and have the AI securely execute the action through the server. The SMS MCP Server built into Ozeki SMS Gateway also makes receiving SMS messages possible.
Download Ozeki SMS Gateway
To use this solution you need to install the SMS Gateway on your system.
Download the software: SMS Gateway
https://ozeki-sms-gateway.com/p_727-download-sms-gateway.html
Steps to follow
You will need Claude Cowork installed on your system, you can download it from here: Claude Cowork.
- Install Ozeki SMS Gateway
- Setup the SMPP SMS connection
- Create an MCP user account
- Claude Cowork SMS MCP Server Config
- Add the SMS MCP Server config to Claude Cowork
- Send a test SMS
- Check the SMS in the SMS Gateway logs
Install Ozeki SMS Gateway
For a full tutorial on installing Ozeki SMS Gateway, check out our How to install Ozeki SMS Gateway on Windows guide.
Before you can use the SMS MCP Server, you need to install Ozeki SMS Gateway on your Windows machine or server. Download the installer zip file from the website, extract it, and run the executable to complete the installation. Once installed, the gateway will start automatically and its web-based management interface will be accessible from your browser.
Setup the SMPP SMS connection
For a full tutorial on setting up an SMPP Client connection, check out our SMPP Client Connection guide.
Before creating the MCP user, you need to connect Ozeki SMS Gateway to the mobile network by setting up an SMPP client. In the Connections panel, select Add new connection, and install a new SMPP client connection. Enter the host, port, and credentials provided by your SMS service provider, then save and activate the connection to bring the gateway online.
Create an MCP user account
For a full tutorial on creating an MCP User, check out our Create an MCP User guide.
Click Add new user/application, and select the MCP user type from the list. Enter a username and password for the account, then open the Advanced tab to generate an API key. Copy this key and store it in a safe location, as you will need it in the next steps.
Claude Cowork MCP server configuration
# Open: Settings -> Developer -> Edit Config -> claude_desktop_config.json
# Replace {address} with your Ozeki SMS Gateway host IP or hostname
# Replace ozk-abc123 with the API key generated for your MCP user account
"mcpServers": {
"ozeki-sms": {
"command": "uvx",
"args": [
"mcp-proxy",
"--transport", "streamablehttp",
"-H", "Authorization", "Bearer ozk-abc123",
"http://{address}:9529/mcp"
]
}
}
Example prompt
Send an SMS to +36301234567, the message should be "Hello from Claude Cowork".
Add the SMS MCP Server config to Claude Cowork
The following video shows how to add the Ozeki SMPP SMS MCP Server to Claude Cowork step-by-step.
Open Claude and navigate to Settings. Select the Developer section and click Edit Config to open the configuration directory in File Explorer (Figure 1).
In the configuration directory, locate and open the claude_desktop_config.json
file in a text editor such as Notepad or Visual Studio Code. This file stores all
MCP server registrations for Claude Cowork (Figure 2).
Add the Ozeki SMS MCP server entry inside the mcpServers block as
shown below. Replace {address} with the IP address or hostname of
your Ozeki SMS Gateway installation, and replace ozk-abc123 with the
API key you generated for your MCP user account. The entry uses
uvx and mcp-proxy to bridge the Streamable HTTP
transport used by the gateway. Save the file after making the changes (Figure 3).
"mcpServers": {
"ozeki-sms": {
"command": "uvx",
"args": [
"mcp-proxy",
"--transport", "streamablehttp",
"-H", "Authorization", "Bearer ozk-abc123",
"http://{address}:9529/mcp"
]
}
}
Restart Claude to apply the updated configuration. Claude Cowork will reload the config file on startup and attempt to connect to the registered MCP servers (Figure 4).
After Claude restarts, open the Connectors panel and confirm that ozeki-sms appears with a connected status. This confirms that the application has successfully reached your Ozeki SMS Gateway using the configured URL and API key (Figure 5).
Send a test SMS
The following video shows how to send an SMS message from Claude Cowork using the Ozeki SMPP SMS MCP server step-by-step.
Type a plain language instruction in the Claude Cowork chat prompt asking the AI to send an SMS to a specific phone number. Claude will interpret the request and call the appropriate MCP tool to deliver the message (Figure 6).
Send an SMS to +36301234567, the message should be "Hello from Claude Cowork".
Claude Cowork 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 Claude to send the SMS (Figure 7).
You will see the result of the Send SMS tool call in the chat window. A successful response confirms that the message has been passed to the gateway and queued for delivery (Figure 8).
Check the SMS in the SMS Gateway logs
The following video shows how to check the SMS in the logs in Ozeki SMS Gateway step-by-step.
Open Ozeki SMS Gateway in your browser and navigate to the MCP user details page by clicking on the MCP user entry in the Users and applications panel (Figure 9).
In the MCP user event log, you should see an entry for the outgoing message, including the recipient number and message text, confirming that it was successfully processed by the gateway (Figure 10).
Summary
In this guide, you have learned how to connect Claude Cowork to Ozeki SMS Gateway's built-in SMS MCP Server and use it to send SMS messages directly from the chat interface. By installing the gateway, setting up an SMPP connection to the mobile network, creating an MCP user account, and registering the MCP endpoint in Claude Cowork, you now have a fully functional on-premises SMS integration that your locally hosted AI model can use to communicate with any mobile phone.