the main means by which users are expected to initiate Loop calls on desktop is via the "Address Book" sidebar, which will contain a list of the user's contacts. For the initial versions of Loop, contacts will can be populated from several sources, via a one-way synchronization (that is, the data will be imported from a remote authority and updated from that remote authority, but cannot be changed by the Loop client). A necessary implication of this setup is that all contacts will need to track which data source they belong to, and be updated only from those sources.
'''Currently Proposed Sources''':
* Data local the the browser (this will be the only editable contact data)
* [https://developers.google.com/google-apps/contacts/v3/ Google] (MVP)