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... :
NXTL i800 Smart PTT Device. Two Way Cellular Radio Hybrid With Full GPS Tracking & Global Coverage. | Eventtone
Nextel makes leap into 21st century
When Phones Were Fun: NEXTEL - YouTube
Motorola Nextel i880 Repair - iFixit
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History and Stuff
Motorola i560 Rugged Nextel Phone Announced - ecoustics.com
Motorola / Nextel I355 Iden Cell 2-way Radio for sale online | eBay
Nextel i95cl review: Nextel i95cl - CNET
Best Nextel Walkie Talkie Reviewed - Transceiver Radio
Direct PTT - The Nextel T320 is the full package. This model is a Smart- Radio with PTT & 2-Way Manage your entire fleet from your palm with full GPS Tracking and Mapping.
Child Of The 80s & 90s - Chirp sound of the Nextel made me feel so official | Facebook
Best Nextel Walkie Talkie Reviewed - Transceiver Radio