Как разрешить только цифры в текстовом поле, если при попытке ввода алфавитов должно отображаться сообщение в веб-форме. C# ASP.NET

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я хочу разрешить только цифры в текстовом поле, кроме того, что число должно принимать, я имею в виду, что не должно позволять печатать, messege должен отображаться.

<%@ Page Title="" Language="C#" MasterPageFile="~/Expense.Master" AutoEventWireup="true" CodeBehind="Register.aspx.cs" Inherits="Expense_System.Register" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">
    <style type="text/css">
        .auto-style1 {
            width: 39%;
        }
        .auto-style2 {
            text-align: right;
            width: 138px;
        }
        .auto-style3 {
            text-align: left;
            width: 143px;
        }
        .auto-style4 {
            text-align: right;
            width: 138px;
            height: 30px;
        }
        .auto-style5 {
            text-align: left;
            height: 30px;
            width: 143px;
        }
        .auto-style7 {
            text-align: right;
            width: 138px;
            height: 29px;
        }
        .auto-style8 {
            text-align: left;
            height: 29px;
            width: 143px;
        }
        .auto-style10 {
            text-align: right;
            width: 138px;
            height: 27px;
        }
        .auto-style11 {
            text-align: left;
            height: 27px;
            width: 143px;
        }
        .auto-style13 {
            text-align: right;
            width: 138px;
            height: 28px;
        }
        .auto-style14 {
            text-align: left;
            height: 28px;
            width: 143px;
        }
        .auto-style16 {
            text-align: left;
            height: 27px;
            width: 165px;
            margin-left: 80px;
        }
        .auto-style17 {
            text-align: left;
            width: 165px;
        }
        .auto-style18 {
            text-align: left;
            height: 29px;
            width: 165px;
        }
        .auto-style19 {
            text-align: left;
            height: 28px;
            width: 165px;
        }
        .auto-style20 {
            text-align: left;
            height: 30px;
            width: 165px;
        }
    </style>
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">

    
    <asp:Menu ID="Menu1" runat="server" BackColor="#FFFBD6" DynamicHorizontalOffset="2" Font-Names="Verdana" Font-Size="0.8em" ForeColor="#990000" Orientation="Horizontal" RenderingMode="Table" StaticSubMenuIndent="10px" style="font-weight: 700; color: #FFFFFF; background-color: #99CCFF; font-size: xx-large; text-align: center;" Width="99%" Height="67px">
                <DynamicHoverStyle BackColor="#990000" ForeColor="White" />
                <DynamicMenuItemStyle HorizontalPadding="5px" VerticalPadding="2px" />
                <DynamicMenuStyle BackColor="#FFFBD6" />
                <DynamicSelectedStyle BackColor="#FFCC66" />
                <Items>
                 <%--   <asp:MenuItem NavigateUrl="~/HomePage.aspx" Text="Home Page" Value="Home Page"></asp:MenuItem>--%>
                    <asp:MenuItem NavigateUrl="~/Loginpage.aspx" Text="Login" Value="Login"></asp:MenuItem>
                </Items>
                <StaticHoverStyle BackColor="#990000" ForeColor="White" />
                <StaticMenuItemStyle HorizontalPadding="5px" VerticalPadding="2px" />
                <StaticSelectedStyle BackColor="#FFCC66" />
            </asp:Menu>
  

    <h1> Fill the below details to register</h1>

    <table class="auto-style1" border="1">
        <tr>
            <td class="auto-style10">Full Name:</td>
           
            <td class="auto-style16">
                <asp:TextBox ID="tbfullname" runat="server" Width="160px" ></asp:TextBox>     
            </td>

            <td class="auto-style11">
                <asp:RequiredFieldValidator ID="RequiredFieldValidatorName" runat="server" controltovalidate="tbfullname" ErrorMessage="Name is mandatory" ForeColor="Red"></asp:RequiredFieldValidator>
            </td>
        </tr>
        <tr>
            <td class="auto-style2">Email id:</td>
            <td class="auto-style17">
                <asp:TextBox ID="tbemail" runat="server" TextMode="Email" Width="160px"></asp:TextBox>
            </td>
            
            <td class="auto-style3">
                <asp:RequiredFieldValidator ID="RequiredFieldValidatormail" runat="server" ControlToValidate="tbemail" ErrorMessage="Email Required" ForeColor="Red"></asp:RequiredFieldValidator>
                <asp:RegularExpressionValidator ID="RegularExpressionValidatormail" runat="server" ControlToValidate="tbemail" ErrorMessage="invalid email" ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*" ForeColor="Red"></asp:RegularExpressionValidator>
            </td>
        </tr>
        <tr>
            <td class="auto-style7">Phone Number:</td>
            <td class="auto-style18">
                <asp:TextBox ID="tbphoneno" runat="server" TextMode="Phone" Width="160px" OnTextChanged="tbphoneno_TextChanged" ></asp:TextBox> 
            </td>
            <td class="auto-style8">
                <asp:RegularExpressionValidator ID="RegularExpressionValidatorphoneno" runat="server" ControlToValidate="tbphoneno"  ErrorMessage="Phone number is invalid" ValidationExpression="[0-9]{10}" ForeColor="Red"></asp:RegularExpressionValidator>
                <asp:RequiredFieldValidator ID="RequiredFieldValidatorphoneno" runat="server" ControlToValidate="tbphoneno" ErrorMessage="Phone number is Required" ForeColor="Red"></asp:RequiredFieldValidator>
                
            </td>
        </tr>
        <tr>
            <td class="auto-style13">Date of birth:</td>
            <td class="auto-style19">
                <asp:TextBox ID="tbdob" runat="server" TextMode="Date" Width="160px"></asp:TextBox>
            </td>
            <td class="auto-style14">
                <asp:RequiredFieldValidator ID="RequiredFieldValidatordob" runat="server" ControlToValidate="tbdob" ErrorMessage="Date of birth is Required" ForeColor="Red"></asp:RequiredFieldValidator>
            </td>
        </tr>
        <tr>
            <td class="auto-style2">Login id:</td>
            <td class="auto-style17">
                <asp:TextBox ID="tbloginid" runat="server" Width="160px"></asp:TextBox>
            </td>
            <td class="auto-style3">
                <asp:RequiredFieldValidator ID="RequiredFieldValidatorloginid" runat="server" ControlToValidate="tbloginid" ErrorMessage="Login id is Required" ForeColor="Red"></asp:RequiredFieldValidator>
            </td>
        </tr>
        <tr>
            <td class="auto-style4">Password:</td>
            <td class="auto-style20">
                <asp:TextBox ID="tbpwd" runat="server" TextMode="Password" Width="160px"></asp:TextBox>
            </td>
            <td class="auto-style5">
                <asp:RequiredFieldValidator ID="RequiredFieldValidatorpwd" runat="server" ControlToValidate="tbpwd" ErrorMessage="password is Required" ForeColor="Red"></asp:RequiredFieldValidator>
            </td>
        </tr>
        <tr>
            <td class="auto-style4">Confirm Password:</td>
            <td class="auto-style20">
                <asp:TextBox ID="tbconfirmpwd" runat="server" TextMode="Password" Width="160px"></asp:TextBox>
            </td>
            <td class="auto-style5">
                <asp:RequiredFieldValidator ID="RequiredFieldValidatorconpwd" runat="server" ControlToValidate="tbpwd" ErrorMessage="Password is Required" ForeColor="Red"></asp:RequiredFieldValidator>
            </td>
        </tr>
        <tr>
            <td class="auto-style4"> </td>
            <td class="auto-style20">
                <asp:Button ID="btnRegsubmit" runat="server" Text="SignUp" OnClick="btnRegsubmit_Click" />
                <input id="RegReset" type="reset" value="Reset" /></td>
            <td class="auto-style5">
                 </td>
        </tr>
    </table>

  

    </asp:Content>

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


namespace Expense_System
{
    public partial class Register : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
         

        }

        protected void btnRegsubmit_Click(object sender, EventArgs e)
        {
        
            String strConnString = ConfigurationManager.ConnectionStrings["conString"].ConnectionString;

            SqlConnection con = new SqlConnection(strConnString);

            con.Open();

            SqlCommand cmd = new SqlCommand();

            cmd.CommandType = CommandType.StoredProcedure;

            cmd.CommandText = "[dbo].[SpCreateUser]";

            cmd.Parameters.Add("@Full_name", SqlDbType.VarChar).Value = tbfullname.Text;
            cmd.Parameters.Add("@Dob", SqlDbType.Date).Value = tbdob.Text;
            cmd.Parameters.Add("@email", SqlDbType.VarChar).Value = tbemail.Text;
            cmd.Parameters.Add("@phoneno", SqlDbType.Int).Value = tbphoneno.Text;
            cmd.Parameters.Add("@loginid", SqlDbType.VarChar).Value = tbloginid.Text;
            cmd.Parameters.Add("@pwd", SqlDbType.VarChar).Value = tbpwd.Text;

            cmd.Connection = con;

            int totalrecordscreated =(int)cmd.ExecuteNonQuery();
            Response.Write("No of created records " + totalrecordscreated.ToString());


            con.Close();
    
           
      

        }

        protected void tbphoneno_TextChanged(object sender, EventArgs e)
        {
            if (!Regex.IsMatch(tbphoneno.Text,
  @"(^([0-9]*|\d*\d{1}?\d*)$)"))
            {
                
            }
            else
            {

            }
        }

      

      
    }
}

Что я уже пробовал:

 protected void tbphoneno_TextChanged(object sender, EventArgs e)
      {
          if (!Regex.IsMatch(tbphoneno.Text,
@"(^([0-9]*|\d*\d{1}?\d*)$)"))
          {

          }
          else
          {

          }

Правильно ли это? но не подтверждаю.

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