POST /registrations                with: phone_number=string, registration_id=number
  -- Register your phone number
PUT  /contact_list                 with: contacts[0]=string, contacts[1]=string, contacts[2]=string, ..., contacts[n]=string
  -- send your contacts, get whether they are operators
GET  /contact_lists/:phone_number  with: my_phone_number=string
  -- request the contacts for an operator
PUT  /contact_lists                with: contacts=XML_for_contacts
  -- send your contacts
GET  /contact_lists/:phone_number   with: my_phone_number=string
  -- demand the contacts for an operator
GET  /contacts/:id                 with: my_phone_number=string
  -- request the contact info for a given id
PUT  /contacts/:id                 with: contact=XML_for_contact
  -- send the contact info for a given id
GET /contacts/:id                  with: my_phone_number=string
  -- demand the contact info for a given id


Where:

XML_for_contacts:

  <contacts>
    <contact id="1" phone-number="6176060842" />
  </contacts>

XML_for_contact:

  <contact>
    <email></email>
    <phone></phone>
    <whatever></whatever>
  </contact>