Sinch Qualified Numbers API
You can use the Qualified Numbers API to qualify numbers you want Sinch to host and have available for use with Sinch SMS services. Qualifying a number involves verifying ownership of a number either by providing a one time passcode sent to the number by voice call or by providing invoices for multiple numbers. Once numbers are qualified, you can then enable those numbers for SMS text messaging services. Note: The SMS enablement process is only supported in United States and Canada.