This billing system also qualifies as an actor. (See, an actor doesn’t have to be a person — it’s anything that interacts with the system but is outside of the system.)
Mfumo huu bili pia qualifies kama muigizaji. (Angalia, muigizaji hana na kuwa mtu â € “”ni kitu chochote ambacho inaingiliana na mfumo lakini ni nje ya mfumo.)