Understanding WhatsApp Coexistence (Coex): Run the Mobile App & Cloud API on One Number

1. What is WhatsApp Coexistence (Coex)?

In Meta’s official WhatsApp Business Platform documentation (documented under Meta Help Center article 524220081677109), WhatsApp Coexistence represents the biggest architectural shift since the introduction of the Cloud API.

Before Coexistence, if a merchant or business owner used the WhatsApp Business smartphone app with their primary SIM phone number and wanted to connect to a WhatsApp Solution Provider (like Tomio) to send high-volume broadcast campaigns or automated OTPs, Meta required them to permanently delete their WhatsApp account from the mobile phone. Once deleted, the number could only be accessed via web software and API endpoints—depriving the business owner of the quick, familiar mobile app experience.

With WhatsApp Coexistence, you no longer delete your mobile account. Meta links your existing WhatsApp Business App account directly to a WhatsApp Business Account (WABA) on the Cloud API. Both channels operate concurrently on the exact same phone number.

2. The 3 Meta Embedded Signup Routing Options

When onboarding a phone number to Meta through an official Solution Provider like Tomio, Meta’s Embedded Signup flow offers three distinct routing methods depending on your business model and infrastructure:

3. Technical Architecture & Webhook Echoes

How does Meta synchronize conversations when two independent clients (the mobile app on iOS/Android and the Tomio Cloud API engine) share a single identity?

The magic lies in Meta’s Message Echoes pipeline (specifically, the smb_message_echoes webhook subscription):

{
  "object": "whatsapp_business_account",
  "entry": [{
    "id": "WABA_ID_987654321",
    "changes": [{
      "field": "smb_message_echoes",
      "value": {
        "messaging_product": "whatsapp",
        "metadata": {
          "display_phone_number": "15551234567",
          "phone_number_id": "PHONE_ID_123456789"
        },
        "message_echoes": [{
          "from": "15551234567",
          "to": "919876543210",
          "id": "wamid.HBgLMTE1NTUxMjM0NTY...",
          "timestamp": "1730460000",
          "type": "text",
          "text": {
            "body": "Hi there! I just checked your order status from my phone."
          }
        }]
      }
    }]
  }]
}

When you send a message from the mobile app, Meta immediately dispatches an echo to Tomio. Our webhook receiver processes this idempotently, matches the contact by customer WhatsApp ID, and renders the message in the Tomio Shared Inbox with a 📱 Mobile App Echo badge.

Likewise, when Tomio sends an automated campaign or customer service reply via Cloud API, Meta reflects that outbound message into your smartphone’s chat history!

4. Pricing Split: Free Mobile Chats vs API Fees

One of the most powerful financial advantages of WhatsApp Coexistence is Meta’s strict separation between App-initiated and API-initiated traffic:

5. The Meta 14-Day Smartphone Inactivity Rule

To maintain the integrity and security of physical mobile devices, Meta enforces a strict rule:

“The WhatsApp Business App on the primary smartphone must be opened at least once every 14 days. If the app is not opened within 14 days, Meta automatically disconnects the coexistence link.”

Why does Meta do this? Because a mobile app that hasn’t synced in 14 days is treated by Meta’s security infrastructure as potentially lost, stolen, or decommissioned.

How Tomio Protects You: In your Tomio Dashboard under Settings > WhatsApp Configuration, we track your mobile app heartbeat. If your last activity was more than 10 days ago, Tomio surfaces an alert warning you to open your phone app before Meta disconnects the bridge.

6. Guardrails, Limitations & OBA Green Tick

While WhatsApp Coexistence provides the best of both worlds, there are specific platform boundaries you should understand:

• Group Chats: In accordance with Meta Cloud API design, group chats initiated or participated in on your smartphone app do NOT mirror to the Cloud API or Tomio inbox.
• Disappearing Messages: Chats with disappearing messages enabled may not mirror consistently across both clients.
• WhatsApp Web / Desktop: You can still link companion devices (e.g. WhatsApp Web or Mac/PC desktop client) using your phone’s QR code, up to Meta’s multi-device limit.
• Official Business Account (Green Tick): Numbers operating under Coexistence remain fully eligible to apply for Meta’s Official Business Account (OBA) green verified checkmark.

7. How to Connect Coexistence in Tomio

Setting up Coexistence takes less than 2 minutes: