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Validation of telephone numbers

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Thanks to Foxentry, you can easily verify the existence of a telephone number and its ability to receive calls or messages. We don't blindly verify the format of the number - we directly verify it. We are also able to find out other information such as the current operator and the type of telephone line. Phone number validation is divided into basic and advanced (default).

Key features - basic validation

  1. Checking the format of the entered number - we check whether the number contains incorrect characters and whether it contains all the necessary digits.
  2. Automatic completion of the area code - we validate telephone numbers even without the area code filled in. Such a number is validated according to the default country (default setting of the Czech Republic).
  3. International numbers - we validate not only Czech numbers, but also international ones.
  4. Callback after validation - after each insertion of a telephone number into the form, Foxentry can trigger a developer-defined action. You can respond to valid or invalid numbers yourself.
  5. Appearance settings - you can easily set most properties directly in our administration. More complex adjustments can be solved using CSS. In the administration, you can easily edit:
  • display of info messages and statuses
  • the behavior of the individual fields in your form
  • direction to the next field after filling
  1. Setting limits - in the administration, you have the option to set the maximum number of requests per day, allowed IP addresses, or URLs where Foxentry can be displayed.
  2. Secure transmission via SSL - all communication with our server is encrypted. No third party can access the data. We store only anonymized data (for example, the number +420798 ******), which is used only for the correct deduction of credits and for your control.

Key features - advanced validation

Advanced validation has all the features of basic validation and these additional features:

  1. A real check of the existence of a number - in a second, we're able to find out if the number really exists.
  2. Ability to receive calls and messages - we can find out if the number is able to receive calls or messages.
  3. Filling in hidden fields of the form - after sending the form, Foxentry can fill in hidden fields with additional information - please see below.
  4. Operator information - for each number, we're able to recognize the operator.
  5. Line type - we can recognize whether the number is a landline or mobile line.


To use it in the web form, you need to:

For installation in applications, internal systems, etc., visit our API page.

Still having trouble? Leave us a note.