SMS and WhatsApp both use the same phone number to identify contacts. When you add a mobile number, choose which channels (SMS, WhatsApp, or both) each number should be subscribed to.
Before you start
Things you need to know:
By default, SMS is selected, so phone numbers uploaded or added via API v3 without a different status are subscribed only to SMS. To also subscribe them to WhatsApp, set the WhatsApp option to Yes.
You must have at least one mobile channel set to Subscribed. You can't set both SMS and WhatsApp to Not Subscribed.
Set mobile subscription defaults
Go to Settings > Contacts > Subscription settings > Mobile subscription settings.
Under Mobile subscription settings, choose your default channels:
SMS - selected by default.
WhatsApp - expand the drop-down menu and select Yes or No.
Select SAVE.
When defaults are applied
When you upload new phone numbers in bulk or through API v3, the chosen channels are marked as subscribed for those numbers, unless you specify a different subscription status for each channel in your request.
If you bulk upload numbers that already exist in your contact list, the settings subscribe them to the selected channels, unless SMS or WhatsApp for those contacts are already Unsubscribed or Suppressed.
Example:
SMS: Yes, WhatsApp: No = New numbers are subscribed to SMS only.
SMS: Yes, WhatsApp: Yes = New numbers are subscribed to both SMS and WhatsApp.
SMS: No, WhatsApp: Yes = New numbers are subscribed to WhatsApp only.
Forms subscription settings
For Pages, surveys, and forms, set channel subscriptions directly on each form. When you add a text field to capture a phone number, choose which mobile channels (SMS, WhatsApp, or both) those numbers should be subscribed to.