If you use GNSS (Global Navigation Satellite System), you can decide whether the data is collected by a separate on-board unit (OBU) or by the customer’s smartphone. The latter option in particular unites cost-efficiency with performance, minimal implementation effort, and ease of extensibility.
For charging purposes, the GPS coordinates are sent to a central processing center, where the exact toll is calculated and the customer billed accordingly. The use of smartphone apps means there's no need to invest in expensive end devices. However, the use of fixed, mobile, and semi-fixed systems is essential to enforcing toll collection with this solution. No in-road equipment is required.