Within your Account Settings, you may notice a toggle towards the bottom called "Autodetect Contacted vs Voicemail"
Autodetect Contacted is a feature where the system will automatically schedules a follow-up call if it thinks that the agent did not have a conversation with the lead.
You can turn that off and then a follow-up call will only be scheduled if the agent presses the appropriate post-call Whispertext options to specify that they didn't speak to the lead.
Let's say you're getting many unintended calls and the system is calling your customers even though your agents have labeled them as contacted, then your Autodetect may be turned on. If Autodetect Contact is turned off, there will be no other calls scheduled for a lead unless an agent specifically schedules it.