Mobile validation on Textbox

u can validate mobile no as follows using RegularExpressionValidator 
<td>
                <asp:TextBox id="TextBox1" 
                     runat="server"/>
             </td>
             <td>
                <asp:RegularExpressionValidator id="RegularExpressionValidator1" 
                     ControlToValidate="TextBox1"
                     ValidationExpression="\d{10}"
                     Display="Static"
                     EnableClientScript="false"
                     ErrorMessage="Mobile noumer must be 10 numeric digits"
                     runat="server"/>
             </td>
          </tr>
          <tr>
             <td></td>
             <td>
                <asp:Button ID="Button1" text="Validate" 
                     OnClick="ValidateBtn_Click" 
                     runat="server"/>
             </td>

Mobile number textbox validation

string pattern = @"^\d{10}$";
        string data = "111111111111";
        if (Regex.IsMatch(data, pattern))
        {
            Console.WriteLine("Match");
        }
        else
        {
            Console.WriteLine("Not a Match");
        }

Include a reference to the namespace System.Text.RegularExpressions

se regular expression to validate the mobile number

This below expressions will accept the country code as optional and the phone number as 10 digit number.
<script language="JavaScript">

function phone_validate(phone)
{

       var phoneReg = ^((\+)?(\d{2}[-]))?(\d{10}){1}?$;

       if(phoneReg.test(phone) == false)
       {

              alert("Phone number is not yet valid.");

       }
       else
       {

              alert("You have entered a valid phone number!"); 

       }

}

</script>
 
Thanks,