Strip Cisco Jabber tel uri.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;

namespace StripJabberTelUri
{
    class Program
    {
        // Update Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Cisco.Jabber.ITP.telhandler\shell\open\command
        // to: "C:\path\to\StripJabberTelUri.exe" "C:\Program Files (x86)\Cisco Systems\Cisco Jabber\CiscoJabber.exe" -URI %1
        static void Main(string[] args)
        {
            var command = args[0];
            var newArgs = string.Join(" ", args.Skip(1).Select(TransformArg));
            Process.Start(command, newArgs);
        }

        private static string TransformArg(string arg)
        {
            if (!arg.ToLowerInvariant().StartsWith("tel:"))
            {
                return arg;
            }

            var decoded = WebUtility.UrlDecode(new Uri(arg).PathAndQuery);
            var newArg = new StringBuilder(decoded.Length + 4);
            newArg.Append("tel:");
            foreach (var c in decoded)
            {
                if ("0123456789x".Contains(c))
                {
                    newArg.Append(c);
                }
            }
            return newArg.ToString();
        }
    }
}