sinch-number-lookup-api

To detect a SIM swap, perform a phone number lookup by sending an HTTP POST request with the SimSwap feature parameter for an E.164 number. The response returns the recent swap status to help block risky verification attempts.

Reassigned number detection checks disconnects relative to a contact date to identify if a number was reassigned. You need it for contact hygiene to clean marketing lists and avoid sending messages to new device owners.

Carrier and line type detection identifies whether an E.164 number is mobile, landline, or VoIP, and returns the carrier name and network codes. You use this intelligence to route SMS or voice calls through the correct channel.

You can use either Node.js or Python SDKs for number lookup. For other programming languages, you can make direct HTTP POST calls to the lookup endpoint to retrieve carrier, line type, and fraud detection signals.

VoIP detection requires the explicit VoIPDetection feature parameter in the phone validation request. You must specify this along with the E.164 number to return the VoIP likelihood for fraud checks.

A key limitation is that this phone validation accepts one E.164 number per request. To clean bulk marketing lists, you must process numbers individually rather than submitting batch lists for carrier detection and contact hygiene.