It's no accident that Apple chose a yellow icon for its walkie-talkie feature. I dug out my old (2002ish) Nextel with PTT (push to talk). It was all the rage back then... :
ringtones wallpapers free nextel wallpaper
How Ringtones Work | HowStuffWorks
Hart Logística - Rental cars, radios, cell phones and other communication systems
Looking For 2000s Song w/ Beeping Phone Sounds : r/NameThatSong