I have not used the app so I don't know about the settings available. However, if it calls at purely random times during the day, you may not be in a state of mind for such conversations. Whereas in a more "organic" setting, you have primed yourself for it and if the other party is happy to participate, it will probably be more mutually enjoyable.
Last I used Dialup, you subscribe to topics and can choose between different schedules with different frequency. This makes it predictable enough to work. You can always hang up when you get a call.
