title: Checking phone numbers for equivalence
body: <p>What's the best way to check phone numbers in different formats for equivalence?</p>
  
  <p>Different formats:</p>
  
  <p>"(708) 399 7222"</p>
  
  <p>"7083997222"</p>
  
  <p>"708-399-7222"</p>
  
  <p>"708399-7222"</p>
  
  <p>"+1 (708) 399-7222"</p>
  
  <p>"+1 (708)399-7222"</p>
  
  <p><strong>Additional Difficulty:</strong> what if the phone number isn't prefaced by the country code?</p>