All WhatsApp Business API accounts are based on a valid phone number. The following rules apply: 

• You must own this number.
• The number must include a country code and an area code.
• The number must be able to receive a call or SMS for the channel activation.
• The number needs to be 'clean', which means it mustn't have been registered with another WhatsApp user. If you are using a number for the WhatsApp App and would like to use this in the API, it is possible to migrate the number. Please follow the steps in this Phone Numbers Migration article, skipping steps 1, 2 and 8. 

These types of numbers are accepted:

• Landline numbers
• Mobile numbers
• Virtual Mobile Numbers (VMN); Need to be voice-capable to receive the activation token by call. VMNs can be purchased from MessageBird.

These types of numbers are not accepted: 

• Shortcodes
• Numbers with an IVR (automated call menu) attached to it, unless this can be disabled to receive the activation token.
• Toll-free numbers

Note that once your number has been set up for the WhatsApp Business API, this cannot be disconnected. If you have switched from the WhatsApp Business App to the API using the same number and are now looking to switch back, you cannot use your number in the Business App anymore; you will need to connect a new clean number.