Mobile Radio Wireless History

Modern SMR systems offer both a traditional dispatch mode, which allows for walkie-talkie-like voice communications over the air between two or more units, and interconnected mode, which uses the public switched telephone network for a more mobile phone-like experience.

Mobile Radio Early Wireless

Before the cell phone, many commercial businesses relied on (and many still do) specialized mobile radio, or SMR, to communicate with service workers out in the field. While public agencies such as law enforcement agencies had access to mobile radios starting in the late 1920s, commercial licenses weren’t available until the SMR service was established by the FCC in 1979. This opened the door to businesses operating fleets to communicate with their drivers in real time.

Varias Personas [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

Specialized mobile radio systems typically include a base station transmitter and antenna for the dispatch office along with mobile radio units for the field technicians. The mobile radio units could be car- or truck-mounted or handheld. In the early days of SMR, vehicle-mounted units were common. Typical use cases for SMR included dispatching taxis and tow trucks.

Modern SMR systems offer both a traditional dispatch mode, which allows for walkie-talkie-like voice communications over the air between two or more units, and interconnected mode, which uses the public switched telephone network for a more mobile phone-like experience. In dispatch mode, the entire fleet can hear these communications while interconnected mode allows for private conversations.

Motorola was a pioneer in the two-way radio era and a mainstay in police cruisers for decades before SMR was introduced to commercial businesses. Motorola improved upon SMR technology and developed MIRS (Motorola Integrated Radio System), which later became the Integrated Digital Enhanced Network (iDEN), a mobile telecom technology that blended cell phone technology with trunked radio service in 1991. Motorola’s improvements increased the number of users on a single part of the bandwidth dramatical compared to the standard, analog version of SMR.

A company called Fleet Call (at the time) used Motorola’s iDEN network to power its mobile devices, which were marketed to service-based companies such as pest control, mobile auto repair, plumbing, HVAC, cable TV, and uniform companies. Fleet Call’s devices looked and acted much like typical cellular phones of the early 1990s, but with a unique “push to talk” feature that instantly converted the phone into a two-way radio. By 1993, Fleet Call had changed its name to Nextel.

The push-to-talk feature differentiated Nextel phones from the rest of the pack and was seen as a marketing advantage. However, Nextel resisted including this feature on its phones initially but the FCC insisted since the iDEN network was licensed to use bandwidth reserved for dispatch use.

Nextel phones had several advantages in that era: they could be used as pagers, cell phones, and two-way radios depending on the business’s needs at any given time. For example, a dispatcher could send a short text message or alert to call the office at the next opportunity, which was similar to the most advanced pagers of the time. A dispatcher could also call an individual for a private phone conversation or use the push-to-talk function to get a quick status update.

Nextel was later acquired by Sprint in 2005. Sprint abandoned Nextel’s iDEN network in favor of its own CDMA network. In 2013, Sprint decommissioned the iDEN network and integrated the spectrum in the Sprint LTE network.

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Sources:

https://www.fcc.gov/wireless/bureau-divisions/broadband-division/specialized-mobile-radio-service-smr

https://ethw.org/Milestones:One-Way_Police_Radio_Communication,_1928

https://motherboard.vice.com/en_us/article/vb7vk4/roger-that-a-short-history-of-the-walkie-talkie

https://en.wikipedia.org/wiki/IDEN

http://www.company-histories.com/Motorola-Inc-Company-History.html

https://en.wikipedia.org/wiki/Nextel_Communications

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