Phone simulator

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

namespace Phone
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] phones = Console.ReadLine().Split(' ');
            string[] names = Console.ReadLine().Split(' ');
            string dial = string.Empty;
            while (dial != "done")
            {
                dial = Console.ReadLine();
                for (int i = 0; i < names.Length; i++)
                {
                    if (dial == "call "+names[i] || dial == "call "+phones[i])
                    {
                        if (dial == "call " + names[i])
                        {
                            Console.WriteLine($"calling {phones[i]}...");
                            Console.WriteLine(CallingMessage(phones[i]));
                        }
                        else if (dial == "call " + phones[i])
                        {
                            Console.WriteLine($"calling {names[i]}...");
                            Console.WriteLine(CallingMessage(phones[i]));
                        }
                    }
                    if (dial == "message " + names[i] || dial == "message " + phones[i])
                    {
                        if (dial == "message " + names[i])
                        {
                            Console.WriteLine($"sending sms to {phones[i]}...");
                            Console.WriteLine(SmsMessage(phones[i]));
                        }
                        else if (dial == "message " + phones[i])
                        {
                            Console.WriteLine($"sending sms to {names[i]}...");
                            Console.WriteLine(SmsMessage(phones[i]));
                        }
                        else
                        {
                            break;
                        }
                    }
                }
            }
        }
        static string CallingMessage(string phone)
        {
            int sumDigitsPhone = SumDigits(phone);
            string message = string.Empty;
            if (sumDigitsPhone % 2 == 0)
            {
                int mins = (int)sumDigitsPhone / 60;
                int secs = (int)sumDigitsPhone % 60;
                message = $"call ended. duration: {mins:d2}:{secs:d2}";
            }
            else if (sumDigitsPhone % 2 != 0)
            {
                message = "no answer";
            }
            return message;
        }
        static string SmsMessage(string phone)
        {
            int differenceDigitsPhone = DifferenceDigits(phone);
            string message = string.Empty;

            if (Math.Abs(differenceDigitsPhone) % 2 == 0)
            {
                message = "meet me there";
            }
            else if (Math.Abs(differenceDigitsPhone) % 2 != 0)
            {
                message = "busy";
            }
            return message;
        }
        static int SumDigits(string phone)
        {
            char[] newPhone = phone.ToCharArray();
            int sumDigits = 0;
            for (int i = 0; i < newPhone.Length; i++)
            {
                if ((int)newPhone[i] >= 48 && (int)newPhone[i] <= 57)
                {
                    sumDigits += (int)newPhone[i] - 48;
                }
            }
            return sumDigits;
        }
        static int DifferenceDigits(string phone)
        {
            char[] newPhone = phone.ToCharArray();
            int differenceDigits = 0;
            for (int i = 0; i < newPhone.Length; i++)
            {
                if ((int)newPhone[i] >= 48 && (int)newPhone[i] <= 57)
                {
                    differenceDigits += (int)newPhone[i] - 48;
                }
            }
            return differenceDigits;
        }
    }
}