With the Economy Plus package, you purchase all the equipment and pay an annual subscription for the alerts service over a minimum contract of 24 months.
This package is designed for when outdoor and indoor coverage at your location is sufficient.
However, please note that indoor coverage depends on a building's configuration (number of floors, construction standard, and wall thickness), and the materials used in its construction.
Optional Extra:
Consider including the signal booster to ensure you have sufficient indoor coverage. You can always purchase it at a later date after testing your watch at your location.