title: Regular Expression for UK Telephone Number
body: <p>I want VB.NET regular expression for below format</p>
  
  <p><strong>7966-591739</strong></p>
  
  <p>I mean user must have to enter <strong>4</strong> <strong>numeric</strong> characters first then <strong>"-"</strong> and then <strong>6 numeric</strong> characters after that <strong>optional for numeric as well as for characters</strong>. In my case user can also enter</p>
  
  <p>7966-591739 <strong>ext</strong> 562 </p>
  
  <p>7966-591739 <strong>x</strong> 434</p>
  
  <p>Please suggest!</p>