As a Geofence (Anchor watch)
When fcAnchor is Activated the current position is saved and fcAnchor is Active. The current position is checked against the saved position at a user defined interval. If the current position is more than a user defined radius from the saved position an alarm is set. The alarm can be a sound (used as an anchor watch) or an SMS to a predefined number when you are ashore (PRO version only).
As a Tracker
By sending an SMS from your mobile phone (using the fcAnchorRemote app) the phones current position is returned. fcAnchorRemote can also Activate/Deactivate fcAnchor remote. All communication is done via SMS so no data subscription is required.