The Service Resource is currently available as a Public Beta product. This means that some features for configuring your Messaging Service via the REST API are not yet implemented, and others may be changed before the product is declared Generally Available. Messaging Service Configuration through the Twilio Console is Generally Available.
The resources for sending Messages with a Messaging Service are Generally Available.
The PhoneNumber subresource of a Service instance represents a phone number you have associated to the Service.
When sending a message with your Messaging Service, Twilio will select a phone number from the service for delivery.
Inbound messages received on any phone number associated to a Messaging Service are passed to the inbound request URL of the Service with the TWiML parameters that describe the message.
Create a PhoneNumber Resource (Add a Phone Number to a Messaging Service)
POST https://messaging.twilio.com/v1/Services/{ServiceSid}/PhoneNumbers
Add a Phone Number to your Messaging Service by creating a PhoneNumber resource.
Each Service can have no more than 400 phone numbers by default. If you think you might need a higher limit, contact Twilio Support about a Messaging Service number limit increase, and include an explanation of your use case.
Removing a phone number from the Service does not release the number from your account. You must release a phone number from your Account to disassociate and delete the phone number from the Service.
Returns a "204 NO CONTENT" if the phone number was successfully removed from the service.