A customer taps the call button on your WhatsApp Business number. Until recently, that call went to a personal mobile, or nowhere at all. With 3CX V20 Update 8, it now rings your call queue, IVR, or AI Agent, the same way a regular phone call would.
WhatsApp voice calling via SIP is a meaningful shift. Customers who prefer WhatsApp as their communication channel can now call your business number from inside the app and reach a properly queued, attended response rather than a dead end.
This guide explains what the feature does, what it cannot do yet, and how to get it working on a Sentire-hosted 3CX instance.
What changed in V20 Update 8
3CX has supported WhatsApp messaging for several years: inbound text messages routed to agent queues, with templates and transfer capabilities. V20 Update 8 extends that same integration to cover voice calls using WhatsApp's SIP implementation over the Meta Cloud API.
The underlying protocol is SIP over TLS with SRTP media encryption and the OPUS audio codec: the same secure call stack used by standard VoIP trunks, adapted to run over Meta's WhatsApp infrastructure.
Inbound only, for now
The current WhatsApp SIP implementation supports incoming calls only. Agents cannot initiate a WhatsApp voice call outbound from 3CX. This matches Meta's current API capabilities and may change in a future update.
What it can do for your business
Routing WhatsApp calls through your PBX gives them the same treatment as any other inbound call. Every destination available to a SIP trunk is available to a WhatsApp call.
Route to a queue
WhatsApp calls join the same ring group or call queue as your regular line. Agents see the call on their 3CX app and answer normally. No separate inbox to monitor.
Send to your IVR
Route WhatsApp calls through the same digital receptionist as your main number. Callers hear your greeting, press a department option, and reach the right team.
Hand off to the 3CX AI Agent
WhatsApp calls can go directly to a 3CX AI Agent for automated handling: answering common questions, capturing details, or escalating to a live agent when needed. This works around the clock, even when no agents are online.
Office hours enforcement
WhatsApp calls respect your 3CX office hours rules. Out-of-hours calls play a voicemail prompt or a custom message rather than ringing unanswered.
Works alongside messaging
If WhatsApp messaging is already configured on your 3CX, adding SIP calling reuses the same Meta app credentials. You do not need to create a separate WhatsApp Business account.
How the call routing works
A WhatsApp SIP call arrives at 3CX as a standard SIP INVITE, delivered from Meta's infrastructure at wa.meta.vc over port 5061 with TLS transport. 3CX processes it against the SIP trunk you create for the WhatsApp number. From that point, normal 3CX routing rules apply: time-based routing, queue priority, agent availability, and call recording all work as expected.
The codec is OPUS, which Meta uses for WhatsApp audio. OPUS delivers good voice quality on variable-bandwidth connections, which matters for callers on mobile data.
What you need before setting it up
The setup spans three systems: Meta's developer portal, the Meta Graph API, and your 3CX admin console. Before starting, confirm you have:
- A WhatsApp Business Platform account with a dedicated phone number (not a personal number) and messaging permissions active in Meta's developer portal
- The Phone Number ID and a User Access Token for that number, available from the Meta for Developers portal or from your existing 3CX WhatsApp messaging config (Admin Console, Voice and Chat)
- A tool for sending API requests, such as Postman or curl, since Meta's UI does not yet expose SIP enabling as a clickable option
- 3CX V20 Update 8 or later. Sentire-hosted 3CX systems on the Sentire cloud are kept current, so this is already in place for Sentire customers.
Setup overview: five steps
The full technical steps are in the 3CX WhatsApp SIP calling guide. At a high level, the process works as follows.
Step 1: Create a WhatsApp Application in Meta's developer portal
If you already have WhatsApp messaging running on 3CX, skip this: your Phone Number ID and User Access Token are already in Admin Console, Voice and Chat. If not, follow the WhatsApp messaging setup guide first to create the Meta app and obtain these two values.
Step 2: Enable SIP on your WhatsApp number via the Graph API
Send a POST request to Meta's Graph API using Postman or curl. The request body specifies your 3CX FQDN and SIPS port (typically 5061). This tells Meta's infrastructure where to send SIP calls. A successful response returns {"success":true}. Each WhatsApp number needs its own POST request.
Step 3: Verify the SIP configuration
Send a GET request to Meta's Graph API to confirm SIP is enabled and the server configuration is correct. The response shows your FQDN, port, and SIP credentials. Keep the SIP user password from this response, as you may need it for trunk authentication.
Step 4: Enable call settings in WhatsApp Business Manager
In WhatsApp Business Manager, navigate to your phone number's Call Settings tab and enable: Allow voice calls, Allow callbacks, and Display call buttons. These controls the call button that customers see on your WhatsApp profile.
Step 5: Create the SIP trunk in 3CX
Download the WhatsApp provider template from the 3CX docs page, import it under Admin, Advanced, Provider Templates, and configure the trunk: set your WhatsApp number as the main trunk number, select the default destination for incoming WhatsApp calls (your queue, IVR, or AI Agent), and uncheck the outbound rule creation option since outbound calling is not supported.
One number, one Meta app
If you have multiple WhatsApp numbers, the entire five-step process must be repeated for each one. Each number needs its own Meta developer app. This is a Meta requirement, not a 3CX limitation.
What this does not cover yet
It helps to be clear on the current boundaries before committing to a deployment.
| Capability | Status |
|---|---|
| Receive inbound WhatsApp voice calls in 3CX | Available |
| Route calls to queues, IVR, AI Agent, or extension | Available |
| Receive WhatsApp messages alongside calls (unified inbox) | Available |
| Make outbound WhatsApp voice calls from 3CX | Not available |
| Send outbound WhatsApp messages from 3CX | Not available (Meta policy) |
| Call recording of WhatsApp calls | Available (standard 3CX recording rules apply) |
Does this work with Sentire-hosted 3CX?
Yes. All Sentire-managed 3CX instances are kept on the current release track. If your instance is on V20 Update 8 or later (which all active Sentire-hosted systems are), the WhatsApp SIP trunk configuration is available today.
The setup requires API calls to Meta's Graph API and a template import in your 3CX admin console. Sentire can handle this end-to-end: we configure the Meta app, enable SIP on the number, set the default call destination, and test a live call before handing over. The process typically takes one to two hours depending on how quickly Meta activates the WhatsApp Business Platform account.
A question worth taking to your team today:
How many customers currently call your WhatsApp number and reach no answer, or a personal mobile that is sometimes off? If the number is more than zero, this configuration is worth an hour of setup time.