*Uncaught TypeError: window.conf.conta.unregister is not a function
    at desregistrar (script.js:145)
    at HTMLButtonElement.onclick (index.html:39)*

window.conf.conta = new SIP.Web.Simple({
    media: {
      remote: {
        video: document.getElementById('remoteVideo'),
        audio: document.getElementById('remoteAudio')
      }
    },
    ua: {
      uri: window.conf.usuario+'@'+window.conf.servidor,
      authorizationUser: window.conf.usuario,
      wsServers: ['wss://'+window.conf.servidor+':8089/ws'],
      password: window.conf.senha,
      displayName: window.conf.nome,
      register : false,
    }
  });