About NumCheckAPI
NumCheckAPI was created as an alternative to traditional SMS messages for verifying a user's phone number during registration, authorization, or verification in various IT projects, websites, or applications.
The NumCheckAPI service allows you to completely abandon expensive SMS messages, replacing them with a cost-effective user authorization method via an incoming call and entering the last four digits of the calling number.
The service can be used as a standalone solution or in combination with an SMS service already used in your project.
Integrating NumCheckAPI into your project allows you to use your budget efficiently and saves up to 90% of SMS messaging costs.
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The call to the user's number arrives much faster than traditional SMS, which can take up to 5 minutes to deliver.
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To get the code, you don't even need to pick up the phone, as the code is visible on the screen during the incoming call.
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Verification requires no additional steps, unlike standard 2FA authorization.
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The user doesn't need to perform complex actions as in the case of outgoing call verification to a special number.
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The user can use any of their phone numbers, including corporate/office numbers or numbers with city prefixes that cannot receive SMS messages.
NumCheckAPI Usage Scenario in Your Project:
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Your service sends us the user's phone number via an API request
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NumCheckAPI calls the client from a number ending with a randomly generated four-digit code. The last 4 digits of the calling number are returned to you in the server response.
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The user receives an incoming call and enters the last 4 digits of the number in your application.
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Knowing the correct code in advance, your side verifies the code's accuracy.
To eliminate issues caused by the user's phone number availability, NumCheckAPI additionally sends you information about the call connection status.
If desired, you can create client identifiers (labels, nicknames, IDs, etc.) for convenient statistics in your personal account and to find the required authorization among others. We can also control the countries to which your users' authorization calls are made.