title: How can i validate json elements relatively to each other?
body: <p>I have a json
  {
    "phone" : "333-444-55-66",
    "mobile" : "333-444-55-66"
  }
  . How can I validate phone and mobile relative? For example, json valid only if first tree number a equals.</p>
  
  <p>{
    "phone" : "<strong><em>333</em></strong>-444-55-66",
    "mobile" : "<strong><em>333</em></strong>-444-55-66"
  } is valid.</p>
  
  <p>{
    "phone" : "<strong><em>777</em></strong>-444-55-66",
    "mobile" : "<strong><em>555</em></strong>-444-55-66"
  } is not valid.
  Thanks.</p>