Actually there are two main places managing the app behavior number blocking considering - settings of the app behavior, and the lists of blocked and allowed numbers. Let's see how it works.
How to protect your voicemail against unwanted calls
Each mobile device is different. In most cases a default settings will work, but sometimes you should try and chose which system works best for you. Here are the available alert types and their features.
Should I Answer for Android offers 3 levels of protection. What are the pros and cons?