> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.pinnacle.sh/v-2/quickstart/sms/ruby/receive/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.pinnacle.sh/_mcp/server.

# Receiving SMS Messages

> Receiving your first SMS with Pinnacle's Ruby SDK

```ruby
require "rcs"
require "sinatra"
require "dotenv/load"

# Load environment variables
API_KEY = ENV["PINNACLE_API_KEY"]
SENDER_NUMBER = ENV["SENDER_NUMBER"]
SIGNING_SECRET = ENV["PINNACLE_SIGNING_SECRET"]

# Initialize the Pinnacle client
client = Pinnacle::Client.new(api_key: API_KEY)

# Endpoint to send SMS
get "/send-sms/:phone_number" do
  begin
    result = client.messages.sms.send_(
        from: SENDER_NUMBER,
        text: "Hello, world!",
        to: params["phone_number"]
    )
    content_type :json
    { message: "SMS sent", id: result.message_id }.to_json
  rescue => e
    content_type :json
    status 500
    { error: e.message }.to_json
  end
end

# Webhook endpoint for inbound SMS
post "/inbound-sms" do
  req_hash = {
    headers: request.env.select { |k, v| k.start_with?("HTTP_") }
                .transform_keys { |k| k.sub(/^HTTP_/, "").split("_").map(&:capitalize).join("-") },
    body: request.body.read
  }

  message_event = client.messages.process(
      req_hash, secret: SIGNING_SECRET
  )

  case message_event.type
    when "MESSAGE.RECEIVED"
      if message_event.message.type == "SMS"
        text = message_event.message.text
        from_number = message_event.conversation.from
        puts "Received message from #{from_number}: #{text}"
        content_type :json
        { status: "received", message_id: message_event.message.id }.to_json
      end
    when "MESSAGE.STATUS"
      puts "Message status: #{message_event.message.status}"
      content_type :json
      { status: message_event.message.status }.to_json
  end
end
```

## Prerequisites

Before proceeding, ensure you have obtained a phone number and API key as described in the [prerequisites](/quickstart/sms).

## Installation

Create a `Gemfile` in your project root:

```ruby
source "https://rubygems.org"
gem "dotenv"
gem "rcs", "2.0.15"
gem "sinatra"
gem "json"
```

Install the dependencies:

```bash
bundle install
```

> **Info**
>
> This guide uses version `rcs 2.0.15`. Requires Ruby version >= 3.3.0

## Configuration

Create an `.env` file in your project root and add your Pinnacle API key and signing secret:

```
PINNACLE_API_KEY="your_api_key" # pnclk_
SENDER_NUMBER="your_phone_number" # +12345678910
PINNACLE_SIGNING_SECRET="your_signing_secret" # pss_
```

## Setting Up a Webhook

To receive inbound SMS messages, you need to configure a webhook in the Pinnacle dashboard:

1. Navigate to **Development > Webhooks** in the Pinnacle dashboard
2. Click **Create new webhook**
3. Give your webhook a descriptive name
4. Enter your webhook endpoint URL
   * For local development, use an ngrok tunnel pointing to port 4567 (port our Sinatra server will run on)
   * For production, use your deployed server URL
5. After creation, copy the **signing secret** and add it to your `.env` file
6. Attach a phone number to your webhook to receive messages. If the number is a sandbox number, ensure that you've whitelisted a number and verified the 4 digit PIN.

> **Info**
>
> Optionally, you can configure custom HTTP headers (e.g. `X-API-KEY`) to be
> sent on every webhook delivery. Add them in the dashboard or via the
> `headers` field on [`POST /webhooks/attach`](/api-reference/webhooks/attach-webhook).
> The `PINNACLE-SIGNING-SECRET` header is reserved.

## Creating Your Webhook Endpoint

Create a new Ruby file (e.g., `server.rb`) and add the following snippet to the right.

The code above creates a Sinatra endpoint that:

* Receives webhook POST requests at `/inbound-sms`
* Verifies the webhook signature using your signing secret
* Processes incoming message events
* Handles both received messages and message status updates

## Running Your Server

Start the Sinatra server:

```bash
ruby server.rb
```

Your server will start on `http://localhost:4567`. If you're using ngrok for local development, start it in a separate terminal:

```bash
ngrok http 4567
```

Use the ngrok URL (e.g., `https://abc123.ngrok.io/inbound-sms`) as your webhook endpoint in the Pinnacle dashboard.

## Testing Your Webhook

Send an SMS to your Pinnacle phone number from any mobile device. You should see the message logged in your server console:

```
Received message from +14155551234: Hello, this is a test!
```

> **Warning**
>
> If you're not receiving any messages, make sure you have a phone number
> associated with your webhook.

Your webhook should now be successfully receiving inbound SMS messages as well message status updates for outbound messages!

For more detail about processing the message payload received, please view the [process method](/methods/process).

Optionally, you can also create the `/send-sms/{phone_number}` endpoint to send an initial SMS message out.

> One API for RCS, iMessage, MMS, and SMS. Build, test, and scale every channel — send your first message in minutes, not weeks.