It will announce who is calling by their name or the phone number if they are not in your contact list. It also will announce who sent you a text or email. It will read it to you, the sms or email subject line, if you want as well. You can customize it to say whatever you want when something comes in. It's a pretty cool app. I assume if you don't have K-9 mail the other features will still work. It's nice to know who sent you stuff without having to look at your phone. Just started using it, but I haven't found a problem with it yet.