An inbound conversation starts when a customer messages your business first. This article covers the key concepts and setup steps to handle inbound conversations on WhatsApp: the 24-hour customer service window, message templates for follow-ups outside that window, entry points that open extended conversation windows, and how respond.io identifies Contacts who use WhatsApp usernames.

Understanding the customer service window

A Customer Service Window is the 24-hour period that opens when a customer initiates a conversation with your business. Replying to the customer opens a service conversation. Once more than 24 hours pass since the customer last messaged, the window closes. To follow up after it closes, send a message template.

Learn more about the Customer Service Window.

Sending a follow-up message template

A WhatsApp message template reopens a conversation with a customer outside the Customer Service Window. Use it to follow up with customers who haven't replied.

Sample message template:

“Hello {{1}}, I’d like to follow up on our previous conversation. Is there anything else you need assistance with? Let me know and I’ll be happy to help.”

Submit the message template for approval before sending.

Adding a WhatsApp button to your Facebook page

Adding a WhatsApp button to a Facebook page is a simple way to receive customer messages. When a customer clicks the button, it opens a free entry point conversation with a 72-hour window — compared to the standard 24-hour Customer Service Window.

Contacts with WhatsApp usernames

Starting July 2026, WhatsApp users can adopt a username. When a Contact uses a username, their phone number is no longer shared with your business. Instead, WhatsApp assigns them a new backend identifier, Business-Scoped User ID (BSUID), to keep conversations connected.

Receiving messages from Contacts with usernames

When a Contact with a username messages your business, respond.io identifies them using their BSUID:

Existing Contacts: Respond.io matches them to their existing record. Their phone number remains the primary identifier, with BSUID stored alongside it.
New Contacts: Contact creation uses BSUID as the primary identifier when there is no phone number available.

Tip: You can request new Contacts to share their phone number via Request phone number button in Marketing and Utility message templates.

Sending messages to Contacts with usernames

Sending outgoing messages will use the phone number as usual. If a Contact only has a BSUID (no phone number available), BSUID becomes the primary identifier. This applies across Workflows, Broadcasts, and Developer API.

Note: Authentication templates must be sent using a phone number. BSUID is currently not supported by Meta for Authentication message templates.

Unsupported message types

When a Contact sends certain types of WhatsApp messages, the content may not display in the Inbox. Instead, it appears as Unsupported message with a JSON payload.

WhatsApp supports some message types that respond.io doesn't yet display. The message is delivered, but its content can't be shown.

The following message types are currently unsupported:

WhatsApp disappearing messages
Edited WhatsApp messages
WhatsApp oversized media files
View-once messages
WhatsApp Flows
Reaction messages

FAQ and Troubleshooting

Why does a WhatsApp message show as sent but the Contact didn’t receive it?

Once WhatsApp accepts a message, delivery depends on the Contact’s availability and account status. Due to privacy and policy restrictions, Meta does not disclose the exact reason for many delivery failures.

This can happen when:

The Contact did not come online within the 30-day period during which Meta holds messages for offline users.
The Contact blocked the business phone number, or another business phone number owned by the business.
The Contact is in a restricted or sanctioned country, or their number is from a restricted or sanctioned country.
The Contact has not accepted WhatsApp’s latest Terms of Service and Privacy Policy.
The Contact is using an outdated version of WhatsApp.
The Contact is part of a Meta experiment group.
The message was sent from one WABA phone number to another WABA phone number — delivery between two WABA numbers is not guaranteed.
Meta did not return the delivered message webhook.
The request contained invalid parameters or encountered an integrity error.

In rare cases, the same message may trigger both a success and a failure webhook update when the Contact is logged in on multiple devices.

What you can do

Reach out through another Channel.
Ask them to send you a new message.
Resend your message within an open conversation window.

For more information, refer to Meta’s documentation on undelivered messages.

Why did I receive the error, “Cannot create message template. This WhatsApp Business Account does not have permission to create messages.”?

This can happen when you attempt to submit a message template but the account hasn’t met Meta’s requirements yet.