Firstly, you apply for a quotation. You will need to give your usual details required for a car insurance quote and you will receive a monthly premium amount
If you accept your quote an appointment will be made to for a technician to visit you and fit your black box tracking device. This price is built into the price of your olicy in most cases.
There is then a period of time where the box gets to know your driving style, it will measure things like braking, cornering, acceleration, speed and the types of roads you drive on. During this period it will be getting an overall feel for your driving skills and tendencies and as such will be assessing your overall risk. You can monitor your driving and what the box is recording remotely to see how you are doing.
The trial periods of the box are different from insurer to insurer but once the data has been gathered, your policy amount will be adjusted accordingly. If you have driven safely and well, then your policy amount should reduce. Conversely, if you have driven recklessly and badly, it may well go up!
If you wish to cancel your insurance, some insurers will charge a fee to have the box removed. There is not a one box fits all for insurers and each insurer will need their own box installed to track you effectively.
Your driving will be constantly monitored on-going and periodically your policy will be updated to reflect how you have driven for the prior period. Whilst this may seem intrusive, safer drivers should benefit from their increased prudence on the roads and this is the only effective way to ensure this happens.