Parsing CSV Phonelist

//Related to question at:
//http://groups.google.com/group/dotnetdevelopment/browse_thread/thread/54f6395f4936d6c9

using System.Linq;
using System.Text;
using System.Collections.Generic;

namespace ConsoleApplication
{
  class PhoneParser
  {
    private const int phoneLength = 10;    // Length of a phone number.
    private const int groupLength = 100;  // Max length of each group of phone numbers.
    private static List<string> inputPhoneList;
    private static int phoneCount;

    static void Main(string[] args)
    {
      inputPhoneList = args[0].Split(',').ToList();
      phoneCount = inputPhoneList.Count();
      int endIdx = phoneCount > groupLength ? groupLength : phoneCount;
      List<string> phoneList = ParsePhoneList(0, endIdx);
      phoneList.ForEach((s) => { Console.WriteLine(s + "\r\n"); });
    }

    private static List<string> ParsePhoneList(int startIdx, int endIdx)
    {
      List<string> pList = new List<string>();
      StringBuilder sb = new StringBuilder(groupLength * phoneLength);
      int i = startIdx;
      while (i < endIdx)
      {
        sb.Append(inputPhoneList[i]);
        if (i < endIdx - 1)
          sb.Append(",");
        i++;
      }
      pList.Add(sb.ToString());
      if (i < phoneCount)
      {
        endIdx += groupLength;
        endIdx = phoneCount > endIdx ? endIdx : phoneCount;
        pList.AddRange(ParsePhoneList(i, endIdx));
      }
      return pList;
    }
  }
}