Phone number regex C#
The regular expressions below can be used to validate if a string is a valid phone number format and to extract a phone number from a string. Please note that this validation can not tell if a phone number actually exists.
The basic international phone number validation
A simple regex to validate string against a valid international phone number format without delimiters and with an optional plus sign:
new Regex("^\\+?[1-9][0-9]{7,14}$")
Enter a text in the input above to see the result
Example code in C#:
using System.Text.RegularExpressions;
using System.Linq;
public class Program
{
public static void Main()
{
// Validate phone number
Regex validatePhoneNumberRegex = new Regex("^\\+?[1-9][0-9]{7,14}$");
validatePhoneNumberRegex.IsMatch("+12223334444"); // returns True
// Extract phone number from a string
Regex extractPhoneNumberRegex = new Regex("\\+?[1-9][0-9]{7,14}");
extractPhoneNumberRegex.Matches("You can reach me out at +12223334444 and +56667778888")
.Cast<Match>()
.Select(m => m.Value)
.ToArray(); // returns {"+12223334444", "+56667778888"}
}
}
The more complex phone number validation
This regular expression will match phone numbers entered with delimiters (spaces, dots, brackets, etc.)
new Regex("^\\+?\\d{1,4}?[-.\\s]?\\(?\\d{1,3}?\\)?[-.\\s]?\\d{1,4}[-.\\s]?\\d{1,4}[-.\\s]?\\d{1,9}$")Enter a text in the input above to see the result
Example code in C#:
using System.Text.RegularExpressions;
public class Program
{
public static void Main()
{
// Validate phone number
Regex validatePhoneNumberRegex = new Regex("^\\+?\\d{1,4}?[-.\\s]?\\(?\\d{1,3}?\\)?[-.\\s]?\\d{1,4}[-.\\s]?\\d{1,4}[-.\\s]?\\d{1,9}$");
validatePhoneNumberRegex.IsMatch("+1 (615) 243-5172"); // returns True
}
}
Extra information about validating phone number
While validation of phone numbers using regex can give a possibility to check the format of the phone number, it does not guarantee that the number exists.
There might be also an option to leave a phone number field without any validation since some users might have:
- More complex phone numbers with extensions
- The different phone numbers for calling them on a different time of day
