Wow. Anyway I'm done posting about Rising on GB for a while, but I think people should know because it's so easy to miss out on the mostly interesting and funny dialogue between Raiden and friends.
For the amateur radio operator achievement trophy:
This Achievement/trophy requires you to listen to at least 400 of the total 540 unique Codec conversations that can occur during the events of the storyline. To hit this total, you will need to make regular visits to the Codec screen to speak with Raiden's allies. As a general rule, you will always find new lines at the start of each File, after major cinematic interludes and during boss battles. Try to visit the screen and speak with all available characters whenever there is narrative event of note: everything from the introduction of a new enemy archetype, to exposition that takes place via automatic Codec exchanges. Once characters repeat a line, there is nothing more to hear at the present time.