Just call this function and enjoy.
It will automatically remove invalid mobile number and provide valid mobile number.
private string convert_to_number(string No)
{
string mobileno = "";
//remove special characters
foreach (char ch in No)
{
if (ch != ' ' && ch != '+' && ch != '-')
{
mobileno = mobileno + ch.ToString();
}
}
//convert to 10 digit
if (mobileno.Length > 10)
{
mobileno = mobileno.Substring(mobileno.Length - 10, 10);
}
return (mobileno);
}