If you don’t want calls between you and someone whose number you have in your CRM to be logged, then you can choose to block that person. To do so, click on “blacklist” in your activities tab. Calls and emails from people who are on your blacklist, will not be logged to your CRM.
You can remove a blacklisted contact in your settings, by managing the blacklist. Swipe left to remove a contact from your blacklist.