Has nothing to do with Encryption. It's when there transmission signal goes all wonky and it actually sounds like a bunch of 0's and 1's missing. Ya know how analog fades in and out, and with digital it just cuts out. That's what he means. Again, nothing to do with Encryption.
the att button just sends a very short data burst from the radio to the site. In a lot of cases the burst will decode at the comm desk where the longer voice packets wont.