Is it the Electronic Product Code (EPC) memory or the user memory?
For electronic toll-collection systems that use passive UHF tags, the serial number encoded in the tag’s EPC memory is read. This number is associated with a specific account in a database, and that account is charged the toll fee whenever that serial number is read. Currently, only a small percentage of bridge and highway operators use passive UHF tags, but that percentage is growing (see Efforts to Aid Adoption of ISO 18000-6C RFID for Toll Collection Move Forward).
—Mark Roberti, Founder and Editor, RFID Journal
Can I Store Multiple RFID Tags on a Single RFID Microchip? »