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... :
Nextel i530 Cell Phone Review - BayReviews
Nextel Phones & Radios | East Northport NY
Motorola's Ruggedised Phone
nextel i88 cell phone i880
Direct PTT - Get The New Nextel i450 Two Way Cellular... | Facebook
Walkie talkie Nextel cellphones... there's an entire generation that doesn't know about these lol : r/nostalgia
MOTOROLA I530 YELLOW RUGGED WALKIE TALKIE NEXTEL OR BOOST MOBILE CELL PHONE - GTIN/EAN/UPC 661799306218 - Product Details - Cosmos