title: Regex that allows dashes and numbers only?
body: <p>What is the regex to allow dashes and numbers only?</p>
  
  <p>A good example is use in a phone number. e.g. 555-555-555, 12-2314-425.</p>
  
  <p>I don't want entries like: <code>-------------</code> though but <code>-34--53-343</code> is fine for now.</p>