How to make a filter for phone numbers by length?

Question

SIM cards

I need the maximum length of the phone number and the minimum without + :)
And how can I check that the number is entered?

Answer 1

The country code is one to three digits. Next - ten digits of a telephone number within the country.
The country code is preceded by a plus sign. Plus in European countries can be replaced by two zeros.
Make a check based on this data. It is advisable to check by country code.