"How to Connect an External SMS API to On-Chat"

Introduction

On-Chat's External API channel integration allows you to connect any custom SMS provider, in-house messaging gateway, or third-party SMS API that is not natively listed in On-Chat. This flexible integration method uses webhooks and API endpoints to route messages from your custom provider into On-Chat's shared inbox, giving your team full access to automation, routing, and reporting features.

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Prerequisites

• An On-Chat account with admin access
• Access to your external SMS provider's API documentation
• API credentials from your SMS provider (API key, token, or username/password)
• Ability to configure webhook/callback URLs in your SMS provider
• Basic understanding of HTTP webhooks and API requests

Step 1: Understand the External API Channel

On-Chat's External API channel acts as a universal SMS inbox connector. Your SMS provider sends inbound messages to On-Chat via a webhook URL, and On-Chat sends outbound replies back to your provider via its API. This two-way communication works with virtually any SMS gateway that supports webhooks and REST APIs.

Step 2: Create an External API Inbox in On-Chat

In On-Chat, go to Settings → Inboxes → New Inbox. Select API or External API as the channel type. Give your inbox a descriptive name (e.g., "Custom SMS Gateway"). Save to generate your On-Chat Webhook URL and API Access Token — you will need these in the next steps.

Step 3: Configure Inbound Messages from Your SMS Provider

In your SMS provider's dashboard, set the inbound message delivery URL to your On-Chat webhook endpoint. When a customer sends an SMS to your gateway number, your provider will POST the message payload to this URL. On-Chat will parse the payload and create a new conversation in the inbox.

Step 4: Configure Outbound Messages via Your SMS Provider's API

In On-Chat, go to your External API inbox settings and add your SMS provider's outbound API endpoint, along with the required authentication headers or parameters (API key, auth token, etc.). On-Chat uses this configuration to send agent replies back to customers through your provider.

Step 5: Map Incoming Message Fields

Ensure your SMS provider's inbound message payload includes the sender's phone number and message body in a format On-Chat can parse. Refer to On-Chat's External API documentation for the expected payload schema, and configure your provider's webhook to match the required format.

Step 6: Assign Agents and Set Up Automation

In On-Chat, navigate to Settings → Inboxes → select your External API inbox → Collaborators. Add agents who will handle the conversations. Set up automation rules to route, tag, or auto-reply to messages as needed.

Step 7: Test and Validate the Integration

Send a test message through your SMS gateway to trigger an inbound webhook event. Verify the message appears in your On-Chat External API inbox. Have an agent reply and confirm the reply is delivered back to the sender via your SMS provider's outbound API.

Best Practices

• Document your SMS provider's payload format and store it in On-Chat's internal notes
• Use On-Chat's API logs to debug webhook delivery issues during setup
• Secure your webhook endpoint with token validation to prevent unauthorized message injection
• Test with multiple phone numbers to ensure bidirectional message flow works reliably