ASP.net/C# help for a fledgling

I am trying to build a small web application in ASP.net that texts our employees when we have an urgent message that we need to distribute.  My idea is that someone with the authority to send one of these messages will login, create a message, and send it.  I have been able to send messages successfully if name a single mobile number to a variable, or even when I assign multiple numbers to an array.  Of course I don't want to go to the code to add/remove numbers, so I have a database with the numbers in it.

This is the part that is frustrating me is that I don't know how to get my data from SQL into my application.  The closest I have gotten appears to assign the current location to my array, I am not even sure how that is happening.

[EDIT: the data I am trying to get from SQL is a single column of integers representing phone numbers.]

Here is my code asking SQL for data:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;

namespace ProjectASPudemy.Pages
{


    public partial class Comms : Page
    {
        private const string cs = "Data Source=ElRando\\SQLE;Initial Catalog=Inventory;Integrated Security=True";
        private const string sql = "SELECT CellPhone, LastName FROM Employees WHERE CellPhone IS NOT NULL AND CurrentEmployee = 1";
        private const int V = 0;

        protected void Page_Load(object sender, EventArgs e)
        {

        }
        protected void btnSMS_Click(object sender, EventArgs e)
        {

            
            SqlConnection con = new SqlConnection(cs);
            Contacts[] aContacts = null;
           
            using (SqlCommand cmd = new SqlCommand(sql, con))
            {
                con.Open();
                using (var reader = cmd.ExecuteReader())
                {
                    var list = new List<Contacts>();
                    while (reader.Read())
                        NewMethod(reader, list);
                    aContacts = list.ToArray();
                    TxtList.Text = list.ToString();
                }

            }

            string contacts = null;
            foreach (var contact in aContacts)
            {
                string number = contact.ToString();
 
                contacts = contacts + contact.ToString() + "\n";
            }
            TxtCells.Text = contacts;

        }
        private static void NewMethod(SqlDataReader reader, List<Contacts> list)
        {
            
            list.Add(new Contacts { CellNumber = (int)reader.GetInt64(V) });
        }
    }
}

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Here is the code for the Contacts class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace ProjectASPudemy.Pages
{
    public class Contacts
    {
        public int CellNumber { get; set; }

        public static implicit operator Int32(Contacts v)
        {
            throw new NotImplementedException();
        }
    }
}

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I created two text boxes so that I can output on the site the data that I think should be cell numbers, but that is not what is returned.  The first image is the TxtCells box which is the result of looping through the List list and placing the values (I was expecting cell numbers) in the text box.  The second image is the TxtList box which I just tried to print the list to without looping (no specific expectation here, just looking for anything I could to figure out why it wasn't working).


I have tooled around, looking for anything that can help and I have implemented a few proposed solutions but I am still having trouble.

Helpful information:
Using Visual Studio 2019/Testing in Edge
I am new to VS, ASP.net, C# and coding in general, so I wouldn't be surprised if I am so far off the beaten path that Lewis and Clark couldn't even find me.  Perhaps this project was a little ambitious for a novice, but since I can't code, ambition is all I got!

I appreciate any help on this, as well as any constructive criticism.