both are similar in a way that it deal with political corruption and revolve around lawyers, court etc. acting from both dramas are superb, especially by those villains. love both male & female leads!

both are crime related dramas with not much love line going on and interesting plots! korea's crime dramas are getting mainstream nowadays but these 2 are the better ones out there. for signal, the highlight is the walkie-talkie while for voice, the highlight is that the femlead can visualise sounds.