Telephone Number Identification (TNI) checks whether a phone number is real and dialable, and reveals details about it — geographic provisioning (country, region, city) and the type of line it's assigned to.
How the broader check works
A related, commonly paired process places an automated call to the consumer while they're checking out, delivering a one-time PIN they then re-enter on the site — proving they actually control that number, not just that the number exists.
What TNI is for
Three things: confirming the number is dialable, surfacing where it's provisioned geographically, and identifying the line type — landline, mobile, or VOIP.
Where it struggles
- Coverage outside the United States is limited
- Fixed VOIP (like Vonage) is hard to distinguish from non-fixed VOIP (like Skype)
- Prepaid mobile numbers can misclassify as standard mobile lines
When a first number fails, the practical response is to prompt for an alternate number rather than declining outright — but repeated verification failures across numbers is itself a meaningful risk signal.