21706: PhoneNumberSid' is required to associate to a Messaging Service.ERROR: 21706error-21706 page anchorERROR Error - 21706error---21706 page anchor PhoneNumberSid' is required to associate to a Messaging Service.phonenumbersid-is-required-to-associate-to-a-messaging-service page anchorYou attempted to add a phone number to your Service, but you forgot to include the SID of the phone number you would like to add.