public static string GetPhoneNumberFromUser()
{
string phoneNumStr = null;
bool inputIsValid = false;
while (inputIsValid == false)
{
Console.WriteLine("Please enter your phone number");
phoneNumStr = Console.ReadLine();
inputIsValid = ClientCard.IsPhoneNumberValid(phoneNumStr);
if (inputIsValid == false)
{
Console.WriteLine("The number must contain 10 digits");
}
}
return(phoneNumStr);
}