Validation of answers in a list question

I have a list question with a maximum of 3 to list telephone numbers.

Three types of telephone numbers are valid:

  1. If the first digit is 0 and the second digit is different from 0 the length should be 9
  2. if the first digit is different from 0 and different from + the length should be 8
  3. otherwise it can be any number

I would like to popup an error message when one of the telephone numbers entered is incorrect. How can I do this validation?

Many thanks

Ana, you can use “string functions”: to formulate your rules.

For example, your rule #1 is something like:
!(phone.StartsWith(“0”) && !phone.StartsWith(“00”) && phone.Length!=9)

your rule #2 is:
!(!phone.StartsWith(“0”) && !phone.StartsWith("+") && phone.Length!=8)

and clearly rule 3 you don’t need as it is the default.

Best, Sergiy Radyakin