A customer may need to switch from chat to a conversation with your team. Your calling integration determines where that call can go and who can answer it.

## Confirm eligibility, call direction and applicable permission

Check the sender’s eligibility, call direction and applicable customer permission. A successful messaging setup does not prove calling is enabled.

## WhatsApp calls cannot connect to the public telephone network

Keep the call on supported application, SIP or WebRTC routes. [Twilio’s WhatsApp Business Calling guide](https://www.twilio.com/docs/voice/whatsapp-business-calling) explains that calls connecting WhatsApp to the public telephone network are rejected:

> Calls from WhatsApp endpoints can't be connected to Public Switched Telephone Network (PSTN) endpoints. Such calls will be rejected.

## Carry the customer’s task into the call and follow-up

Carry the customer’s task and verified context into the call or human handoff. Confirm the actual business action before preparing a follow-up. Send that follow-up when the customer’s permission and messaging rules allow it.

## WhatsApp calling and telephone voice

- [WhatsApp calling](/products/whatsapp/calling).
- [Telephone voice](/products/voice).
- [WhatsApp calling setup](/docs/guides/whatsapp/calling).

## Related resources

- [WhatsApp](/products/whatsapp) (product)
- [Sending WhatsApp messages](/docs/guides/whatsapp/sending-whatsapp) (docs)
- [Connecting WhatsApp to Bird: from buying a number to a live channel](/learn/whatsapp/connecting-whatsapp-to-bird) (video)
- [WhatsApp message builder](/tools/whatsapp-message-builder) (tool)

[Get an implementation brief](/learn/workspace?topic=whatsapp)