Twilio Conversations Classic API

Overview

Conversations (classic) API provides persistent, multi-channel threads where participants on SMS, WhatsApp, and web chat can message together. Unlike single-message APIs, Conversations maintains history and supports multi-agent access.

Note: This is the Conversations (classic) API (v1).

Prerequisites

• Twilio account with Conversations (classic) enabled — New to Twilio? See twilio-account-setup — Enable at: Console > Conversations > Manage > Overview > Enable Conversations
• Environment variables:
  • TWILIO_ACCOUNT_SID
  • TWILIO_AUTH_TOKEN — See twilio-iam-auth-setup for credential setup and best practices
• SDK: pip install twilio / npm install twilio
• For SMS/WhatsApp participants: a Twilio number assigned to a Conversations Service

Setup: Create a Conversation Service (classic)

A Conversation Service is the parent configuration container for all your conversations in the classic API. You need one before creating conversations with SMS/WhatsApp participants.

Python

import os
from twilio.rest import Client

client = Client(os.environ["TWILIO_ACCOUNT_SID"], os.environ["TWILIO_AUTH_TOKEN"])

# Create a Conversation Service
service = client.conversations.v1.services.create(
    friendly_name="Customer Support Service"
)
print(f"Service SID: {service.sid}")

Node.js

const twilio = require("twilio");
const client = twilio(process.env.TWILIO_ACCOUNT_SID, process.env.TWILIO_AUTH_TOKEN);

// Create a Conversation Service
const service = await client.conversations.v1.services.create({
    friendlyName: "Customer Support Service"
});
console.log(`Service SID: ${service.sid}`);

Next: Assign your Twilio phone number to this service at Console > Conversations > Manage > Services > Select your service > Add phone number.

Quickstart

Python

import os
from twilio.rest import Client

client = Client(os.environ["TWILIO_ACCOUNT_SID"], os.environ["TWILIO_AUTH_TOKEN"])

# Create a conversation (use default service or specify service_sid)
conversation = client.conversations.v1.conversations.create(
    friendly_name="Customer Support - Order #12345"
)

# Add an SMS participant
client.conversations.v1 \
    .conversations(conversation.sid) \
    .participants \
    .create(
        messaging_binding_address="+15558675310",
        messaging_binding_proxy_address="+15017122661"
    )

# Send a message
client.conversations.v1 \
    .conversations(conversation.sid) \
    .messages \
    .create(body="Hello! How can I help you today?", author="support-agent")

Node.js

const twilio = require("twilio");
const client = twilio(process.env.TWILIO_ACCOUNT_SID, process.env.TWILIO_AUTH_TOKEN);

// Create a conversation (use default service or specify serviceSid)
const conversation = await client.conversations.v1.conversations.create({
    friendlyName: "Customer Support - Order #12345",
});

// Add an SMS participant
await client.conversations.v1
    .conversations(conversation.sid)
    .participants.create({
        messagingBindingAddress: "+15558675310",
        messagingBindingProxyAddress: "+15017122661",
    });

// Send a message
await client.conversations.v1
    .conversations(conversation.sid)
    .messages.create({ body: "Hello! How can I help you today?", author: "support-agent" });

Key Patterns

Add Participants by Channel

WhatsApp participant — Python

client.conversations.v1 \
    .conversations(conversation.sid) \
    .participants \
    .create(
        messaging_binding_address="whatsapp:+15558675310",
        messaging_binding_proxy_address="whatsapp:+14155238886"
    )

WhatsApp participant — Node.js

await client.conversations.v1
    .conversations(conversationSid)
    .participants.create({
        messagingBindingAddress: "whatsapp:+15558675310",
        messagingBindingProxyAddress: "whatsapp:+14155238886",
    });

Chat participant (web/mobile) — Python

client.conversations.v1 \
    .conversations(conversation.sid) \
    .participants \
    .create(identity="user-123")

Chat participant (web/mobile) — Node.js

await client.conversations.v1
    .conversations(conversationSid)
    .participants.create({ identity: "user-123" });

Send Media (All Channels)

Python

# Send a message with media
client.conversations.v1 \
    .conversations(conversation.sid) \
    .messages \
    .create(
        body="Check out this image!",
        author="support-agent",
        media_url="https://example.com/image.jpg"
    )

# Multiple media URLs (up to 10)
client.conversations.v1 \
    .conversations(conversation.sid) \
    .messages \
    .create(
        body="Here are the documents",
        author="support-agent",
        media_url=[
            "https://example.com/doc1.pdf",
            "https://example.com/doc2.pdf"
        ]
    )

Node.js

// Send a message with media
await client.conversations.v1
    .conversations(conversationSid)
    .messages.create({
        body: "Check out this image!",
        author: "support-agent",
        mediaUrl: "https://example.com/image.jpg"
    });

// Multiple media URLs (up to 10)
await client.conversations.v1
    .conversations(conversationSid)
    .messages.create({
        body: "Here are the documents",
        author: "support-agent",
        mediaUrl: [
            "https://example.com/doc1.pdf",
            "https://example.com/doc2.pdf"
        ]
    });

Media must be publicly accessible URLs. Supported: JPG, PNG, GIF, PDF, vCard. Max 10 URLs per message. Works across all channels: SMS (as MMS), WhatsApp, and chat participants all receive media.

Add Multiple Participants

Python

# Add multiple SMS participants to a conversation
participant_numbers = [
    "+15558675310",
    "+15558675311",
    "+15558675312"
]

twilio_number = "+15017122661"

for phone_number in participant_numbers:
    client.conversations.v1 \
        .conversations(conversation.sid) \
        .participants \
        .create(
            messaging_binding_address=phone_number,
            messaging_binding_proxy_address=twilio_number
        )

Node.js

// Add multiple SMS participants to a conversation
const participantNumbers = [
    "+15558675310",
    "+15558675311",
    "+15558675312"
];

const twilioNumber = "+15017122661";

for (const phoneNumber of participantNumbers) {
    await client.conversations.v1
        .conversations(conversationSid)
        .participants.create({
            messagingBindingAddress: phoneNumber,
            messagingBindingProxyAddress: twilioNumber
        });
}

Fetch Message History

Python

# Get all messages from a conversation
messages = client.conversations.v1 \
    .conversations(conversation.sid) \
    .messages \
    .list(limit=50)

for message in messages:
    print(f"{message.author}: {message.body}")

Node.js

// Get all messages from a conversation
const messages = await client.conversations.v1
    .conversations(conversationSid)
    .messages
    .list({ limit: 50 });

messages.forEach(message => {
    console.log(`${message.author}: ${message.body}`);
});

List Conversations

Python

# List all conversations
conversations = client.conversations.v1.conversations.list(limit=20)

for conv in conversations:
    print(f"{conv.friendly_name} - {conv.sid}")

# Filter by state
active_conversations = client.conversations.v1.conversations.list(
    state="active",
    limit=20
)

Node.js

// List all conversations
const conversations = await client.conversations.v1.conversations.list({ limit: 20 });

conversations.forEach(conv => {
    console.log(`${conv.friendlyName} - ${conv.sid}`);
});

// Filter by state
const activeConversations = await client.conversations.v1.conversations.list({
    state: "active",
    limit: 20
});

Remove Participants

Python

# Remove a participant by participant SID
client.conversations.v1 \
    .conversations(conversation.sid) \
    .participants(participant_sid) \
    .delete()

# Find and remove by phone number
participants = client.conversations.v1 \
    .conversations(conversation.sid) \
    .participants \
    .list()

for p in participants:
    if p.messaging_binding and p.messaging_binding.get("address") == "+15558675310":
        client.conversations.v1 \
            .conversations(conversation.sid) \
            .participants(p.sid) \
            .delete()

Node.js

// Remove a participant by participant SID
await client.conversations.v1
    .conversations(conversationSid)
    .participants(participantSid)
    .remove();

// Find and remove by phone number
const participants = await client.conversations.v1
    .conversations(conversationSid)
    .participants
    .list();

for (const p of participants) {
    if (p.messagingBinding?.address === "+15558675310") {
        await client.conversations.v1
            .conversations(conversationSid)
            .participants(p.sid)
            .remove();
    }
}

Close/Complete Conversations

Python

# Close a conversation (marks it inactive)
client.conversations.v1 \
    .conversations(conversation.sid) \
    .update(state="closed")

# Delete a conversation completely
client.conversations.v1 \
    .conversations(conversation.sid) \
    .delete()

Node.js

// Close a conversation (marks it inactive)
await client.conversations.v1
    .conversations(conversationSid)
    .update({ state: "closed" });

// Delete a conversation completely
await client.conversations.v1
    .conversations(conversationSid)
    .remove();

Handle Incoming Messages (Webhook)

Configure at Console > Conversations > Manage > Global Webhooks.

Security: Always validate the X-Twilio-Signature header in production to confirm requests originate from Twilio. See twilio-webhook-architecture for validation patterns.

Python (Flask)

from twilio.request_validator import RequestValidator

@app.route("/conversations/webhook", methods=["POST"])
def conversations_webhook():
    validator = RequestValidator(os.environ["TWILIO_AUTH_TOKEN"])
    if not validator.validate(request.url, request.form, request.headers.get("X-Twilio-Signature", "")):
        return "", 403

    event_type = request.form.get("EventType")
    conversation_sid = request.form.get("ConversationSid")
    author = request.form.get("Author")

    if event_type == "onMessageAdded" and author != "support-agent":
        client.conversations.v1.conversations(conversation_sid).messages.create(
            body="Thanks — an agent will be with you shortly.",
            author="support-bot"
        )
    return "", 204

Node.js (Express)

app.post("/conversations/webhook", async (req, res) => {
    const valid = twilio.validateRequest(
        process.env.TWILIO_AUTH_TOKEN,
        req.headers["x-twilio-signature"],
        `https://${req.headers.host}${req.originalUrl}`,
        req.body
    );
    if (!valid) return res.status(403).send("Forbidden");

    const { EventType, ConversationSid, Author } = req.body;
    if (EventType === "onMessageAdded" && Author !== "support-agent") {
        await client.conversations.v1
            .conversations(ConversationSid)
            .messages.create({ body: "Thanks — an agent will be with you shortly.", author: "support-bot" });
    }
    res.sendStatus(204);
});

Advanced Context

Message Delivery Status

Track message delivery through webhooks. Configure at Console > Conversations > Manage > Global Webhooks.

Available delivery events:

• onMessageAdded — Message created
• onMessageUpdated — Message status changed
• onDeliveryUpdated — Delivery receipt received (SMS/WhatsApp only)

Python (Flask)

@app.route("/conversations/webhook", methods=["POST"])
def delivery_webhook():
    event_type = request.form.get("EventType")
    
    if event_type == "onDeliveryUpdated":
        delivery_status = request.form.get("DeliveryStatus")
        message_sid = request.form.get("MessageSid")
        print(f"Message {message_sid}: {delivery_status}")
        # Status values: sent, delivered, failed, undelivered
    
    return "", 204

Node.js (Express)

app.post("/conversations/webhook", (req, res) => {
    const { EventType, DeliveryStatus, MessageSid } = req.body;
    
    if (EventType === "onDeliveryUpdated") {
        console.log(`Message ${MessageSid}: ${DeliveryStatus}`);
        // Status values: sent, delivered, failed, undelivered
    }
    
    res.sendStatus(204);
});

Conversation Attributes (Metadata)

Store custom metadata on conversations (order IDs, customer info, tags).

Python

# Set attributes when creating
conversation = client.conversations.v1.conversations.create(
    friendly_name="Customer Support - Order #12345",
    attributes='{"order_id": "12345", "priority": "high", "customer_tier": "gold"}'
)

# Update attributes on existing conversation
client.conversations.v1 \
    .conversations(conversation.sid) \
    .update(attributes='{"order_id": "12345", "status": "resolved"}')

# Read attributes
conv = client.conversations.v1.conversations(conversation.sid).fetch()
import json
attrs = json.loads(conv.attributes)
print(f"Order ID: {attrs['order_id']}")

Node.js

// Set attributes when creating
const conversation = await client.conversations.v1.conversations.create({
    friendlyName: "Customer Support - Order #12345",
    attributes: JSON.stringify({ orderId: "12345", priority: "high", customerTier: "gold" })
});

// Update attributes on existing conversation
await client.conversations.v1
    .conversations(conversationSid)
    .update({ attributes: JSON.stringify({ orderId: "12345", status: "resolved" }) });

// Read attributes
const conv = await client.conversations.v1.conversations(conversationSid).fetch();
const attrs = JSON.parse(conv.attributes);
console.log(`Order ID: ${attrs.orderId}`);

Participant Attributes (Metadata)

Store metadata on individual participants (role, name, account info).

Python

# Set attributes when adding participant
client.conversations.v1 \
    .conversations(conversation.sid) \
    .participants \
    .create(
        messaging_binding_address="+15558675310",
        messaging_binding_proxy_address="+15017122661",
        attributes='{"name": "John Doe", "role": "customer", "account_id": "A123"}'
    )

# Update participant attributes
client.conversations.v1 \
    .conversations(conversation.sid) \
    .participants(participant_sid) \
    .update(attributes='{"role": "vip_customer", "satisfaction": "high"}')

Node.js

// Set attributes when adding participant
await client.conversations.v1
    .conversations(conversationSid)
    .participants.create({
        messagingBindingAddress: "+15558675310",
        messagingBindingProxyAddress: "+15017122661",
        attributes: JSON.stringify({ name: "John Doe", role: "customer", accountId: "A123" })
    });

// Update participant attributes
await client.conversations.v1
    .conversations(conversationSid)
    .participants(participantSid)
    .update({ attributes: JSON.stringify({ role: "vip_customer", satisfaction: "high" }) });

Limits

CANNOT

• Cannot add SMS participants without a Twilio number — Number must be assigned to a Conversations (classic) Service
• Cannot send WhatsApp messages outside the 24-hour window — Subject to service window rules. See twilio-whatsapp-send-message
• Cannot use chat participants without Access Tokens — Client-side SDK auth required. See twilio-iam-auth-setup
• Cannot use WhatsApp Groups API — Deprecated April 2020. Use Conversations (classic) API instead.
• Conversations v1 (classic) is in maintenance mode — Consider Conversations v2 API for new projects with enhanced features and scalability.

Next Steps

• WhatsApp setup and rules: twilio-whatsapp-send-message
• SMS setup: twilio-sms-send-message
• Access Tokens for chat clients: twilio-iam-auth-setup
• Webhook security: twilio-webhook-architecture