1 The default
Voicemail
The phone rings out and a recording asks for a name and number. You listen to it at 6 pm between the last stop and dinner, and call back whoever is still interested.
Where it breaks: a homeowner with a green pool and a party on Saturday is not waiting on a callback — he is dialling the next company on the map while your greeting is still playing. Voicemail is free because it does nothing.