If there are people you just don't want to talk to, or texts you want to stop recieving, you can use the MCleaner app for iPhone. This app has a white list of approved numbers and a black list of disallowed numbers. You can even choose to let in phone calls from one number while letting in their text messages, or vice versa. MCleaner will also log your blocked calls, so you can see who has been trying to get through.
Have an iPhone? See everything that's new with Apple's latest iOS update: