Formatter

src/PhoneNumbers/CountryInfo_NorthAmerica.cs

@@ -192,6 +192,7 @@ public partial class CountryInfo
     {
         CallingCode = "52",
         Continent = NorthAmerica,
+        FormatProvider = MXPhoneNumberFormatProvider.Instance,
         Iso3166Code = "MX",
         Name = "Mexico",
         NdcLengths = new ReadOnlyCollection<int>(new[] { 2 }),

src/PhoneNumbers/Formatters/FormatProviders/MXPhoneNumberFormatProvider.cs

@@ -0,0 +1,20 @@
+namespace PhoneNumbers.Formatters.FormatProviders;
+
+/// <summary>
+/// A <see cref="PhoneNumberFormatProvider"/> for Mexico numbers.
+/// </summary>
+internal sealed class MXPhoneNumberFormatProvider : ComplexPhoneNumberFormatProvider
+{
+    private MXPhoneNumberFormatProvider()
+    {
+    }
+
+    internal static PhoneNumberFormatProvider Instance { get; } = new MXPhoneNumberFormatProvider();
+
+    protected override string ProvideFormat(PhoneNumber phoneNumber, bool international) =>
+        phoneNumber.NationalSignificantNumber!.Length switch
+        {
+            10 => "## #### ####",
+            _ => base.ProvideFormat(phoneNumber, international),
+        };
+}

test/PhoneNumbers.Tests/CountryInfo_NorthAmerica_Tests.cs

@@ -234,7 +234,7 @@ public void CountryInfo_Mexico()
         Assert.False(countryInfo.AllowsLocalGeographicDialling);
         Assert.Equal("52", countryInfo.CallingCode);
         Assert.Equal(CountryInfo.NorthAmerica, countryInfo.Continent);
-        Assert.IsType<ComplexPhoneNumberFormatProvider>(countryInfo.FormatProvider);
+        Assert.IsType<MXPhoneNumberFormatProvider>(countryInfo.FormatProvider);
         Assert.False(countryInfo.IsEuropeanUnionMember);
         Assert.Equal("MX", countryInfo.Iso3166Code);
         Assert.Equal("Mexico", countryInfo.Name);

test/PhoneNumbers.Tests/PhoneNumber_ToString_NorthAmerica_Tests.cs

@@ -79,6 +79,13 @@ public void Grenada_Numbers(string input, string format, string expected) =>
     public void Jamaica_Numbers(string input, string format, string expected) =>
         Assert.Equal(expected, PhoneNumber.Parse(input).ToString(format));
 
+    [Theory]
+    [InlineData("+525550154158", "E.123", "+52 55 5015 4158")]
+    [InlineData("+525550154158", "N", "55 5015 4158")]
+    [InlineData("+525550154158", "RFC3966", "tel:+52-55-5015-4158")]
+    public void Mexico_Numbers(string input, string format, string expected) =>
+        Assert.Equal(expected, PhoneNumber.Parse(input).ToString(format));
+
     [Theory]
     [InlineData("+16644913789", "E.123", "+1 664-491-3789")]
     [InlineData("+16644913789", "N", "(664) 491-3789")]