We've made IO Phone call filters now available. You can make a filter and choose phone as the type to see the available filters. Any phone filters that you save can be applied on the call log page and in automations.
Using them in automations will allow you to do some pretty powerful stuff like sending text messages to missed calls. You can setup a filter as shown below to catch those calls. Remember if you are using templates with variables that there is no guarantee that we can match a missed call to a customer in your database, so the variables may not always populate.
See the video to learn more.