That's a good example. In that case though I'd say that every month the voip line is providing a service. Something like a Netflix subscription that you haven't

That's a good example. In that case though I'd say that every month the voip line is providing a service. Something like a Netflix subscription that you haven't logged into for 6 months is more unequivocally providing no value. Mandatory monthly notifications about charges seem better though and wouldn't lead to weird perverse incentives. (Like Netflix spamming your email with auto-login links so if you click one they can claim you did use their service)