ModelTalker and Acapela are external companies that provide a voice banking service. With these services, you can record a number of phrases which are then used to create a synthetic version of your voice. This voice can then be downloaded for use in Predictable! This can be done via Settings > Speech > Acapela/ModelTalker. Then you can log in with your respective account and download the voice.
You can find Acapela here: https://mov.acapela-group.com/
You can find ModelTalker here: https://www.modeltalker.org/
One thing to bear in mind is that due to technical restrictions, custom Acapela or ModelTalker voices can't be used with the Predictable calling feature.
