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Telephone Identification


Telephone verification is the process of calling back a consumer at the phone number they have provided in order to verify the phone is working and the person in possession of the phone is the one placing the order. It is available as a hosted bureau service.

Key considerations when implementing or buying this functionality include:

  • What countries are supported?

  • How does the service handle unanswered calls?

  • Can the session be handled from within your site or do you have to pass off to another outside session?

  • Look into telephone type authentication, TNI.

  • Look into name, address and phone authentication as well.


Telephone Verification works by automatically calling an online end-user's telephone number at the same time the end-user is making a transaction on a website. The user, while on the website, answers the phone and is provided a one-time personal identification number (PIN), the PIN is randomly generated and must be provided by the end-user to confirm possession of the phone. An otherwise anonymous online end-user will be able to confirm that the person who received the phone call and the person who is interacting on the website are the same person.

Telephone Verification works with a 4-step process:

  1. Merchant requests consumer verification

  2. Automated call is generated to the consumer

  3. Consumer inputs the PIN they received on the phone call into the website

  4. Merchant confirms the PIN and the consumer is verified


If the consumer, or end user, cannot verify through the phone you should prompt them to try again with another phone number. If they cannot pass on further attempts you should assume the consumer or end user is high risk.


Telephone number identification, or TNI, serves several important functions. First it authenticates that the number is a real "dialable" phone number. Second it will let you know where the phone was provisioned: the country, region, and city. Lastly, and most importantly, it will tell you the type of phone the number is assigned to.

NOTE: This is typically an inexpensive service and when coupled with other techniques it can provide a nice return for the money spent to perform the check.

“Gotchas” with phone identification include:

There are very few resources for this type of service, and once outside the U.S. the number is increasingly smaller.

Make sure the service distinguishes fixed VOIP, like Vonage, versus non-fixed VOIP, like Skype.

On mobile phones, not all prepaid phones will be distinguished as such, and some may look like regular mobile phones.



Alternative SolutionsArea code mapping, identity authentication, reverse phone lookups.

Building this In-House - N/A

Estimated Cost - Typically this service is offered on a per-transaction basis. This service is usually fairly inexpensive for USA, but the price can vary dramatically based on the countries you do business in.

Sample Vendors - TeleSign, TNSVerify

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