question: Why won’t “old phone” be able to work in a 5G network? Do we have to get new phones when 5G becomes a more prominent thing?
comment: The way I like to explain it: Think of network technologies like languages. 5G speaks Arabic. 4G speaks Chinese. 3G speaks English. Your phone now only speaks Chinese and English. You will need a new one to understand Arabic. It gets more complex than this, in a technical sense, but the concept is the same.
passages: When South Korea launched its 5G network, all carriers used Samsung, Ericsson and Nokia base stations and equipment, except for LG U Plus, who also used Huawei equipment. Samsung was the largest supplier for 5G base stations in South Korea at launch, having shipped 53,000 base stations at the time, out of 86,000 base stations installed across the country at the time.
   By 2017, Nokia also started resurrecting its classic devices. This began in May 2017 when a new 3310 handset was introduced at the Mobile World Congress. It sported an updated but similar design language to the original, which debuted in September 2000. This device was still a feature phone but it shipped with a fresh operating system, colored display, and Nokia native applications. After the success of this initiative, Nokia again rebooted one of its classic phones, the Nokia 8110, which featured a 4G update, excellent battery life, and classic Nokia apps.
  
  Section::::Reception.
   AT&T shut down its 2G GSM (850/1900 MHz) network on January 1, 2017.
  
  In April 2017, AT&T announced that it would upgrade its existing LTE networks in selected markets to support LTE Advanced and LTE Advanced Pro features, marketed as "5G Evolution" (5G E).
  
  In January 2018, AT&T stated that it intended to deploy 5G NR service by the end of the year.
  
  Section::::Marketing.
  
  Section::::Marketing.:"Fewest dropped calls".
   Like LTE in unlicensed spectrum, 5G NR will also support operation in unlicensed spectrum (NR-U). In addition to License Assisted Access (LAA) from LTE that enable carriers to use those unlicensed spectrum to boost their operational performance for users, in 5G NR it will support standalone NR-U unlicensed operation which will allow new 5G NR networks to be established in different environments without acquiring operational license in licensed spectrum, for instance for localized private network or lower the entry barrier for providing 5G internet services to the public.
  
  Section::::Concerns.
  
  Section::::Concerns.:Interference issues.
   5G NR
  
  5G NR (New Radio) is a new radio access technology (RAT) developed by 3GPP for the 5G (fifth generation) mobile network. It was designed to be the global standard for the air interface of 5G networks.
  
  The 3GPP specification 38 series provides the technical details behind NR, the RAT beyond LTE.
   BULLET::::- LG – KE 520, KF 757 (3G), GT505, Optimus One, LG Optimus Me
  
  BULLET::::- Motorola – DEFY, Z6w
  
  BULLET::::- Nokia – 6300i, 6301, 6301b, 6086, 6136, 7510, E73 Mode, E5, C7 Astound, Lumia 521, Lumia 925, Nokia 1 and other low-cost handsets once WiFi calling is enabled, if necessary via a free third-party 'App'
  
  BULLET::::- Sagem – my419X
  
  BULLET::::- Samsung – SGH-T339, SGH-T409, SGH-T709, SGH-T739 (Katalyst), T336, P250, P260, P270 (3G), T-Mobile's Galaxy S SGH-T959, Galaxy SII SGH-T989, Orange Galaxy SII with NFC (GT-i9100P), T-Mobile's Galaxy S4 SGH-M919 and Galaxy S7 SM-G930T
  
  BULLET::::- Sony Ericsson – G705u (3G)
  
  Section::::Devices.:Routers.
   Ooredoo was the first carrier to launch a commercial 5G NR network in May 2018 in Qatar. Other carriers around the world have been following suit.
  
  Section::::Development.
  
  In 2018, 3GPP published Release 15, which include what is described as "Phase 1" standardization for the 5G NR standard. 3GPP is expected to publish Release 16, which include the "Phase 2" of 5G NR, by the end of year 2019.
  
  Section::::Deployment modes.
  
  Initial 5G NR launches will depend on existing LTE 4G infrastructure in non-standalone (NSA) mode, before maturation of the standalone (SA) mode with the 5G core network.
  
  Section::::Deployment modes.:Non-Standalone mode.
   Large quantities of new spectrum (5G NR frequency bands) have been allocated to 5G in order to support its increased throughput requirements. For example, in July 2016, the U.S. Federal Communications Commission (FCC) freed up vast amounts of bandwidth in underused high-band spectrum for 5G. The Spectrum Frontiers Proposal (SFP) doubled the amount of millimeter-wave unlicensed spectrum to 14 GHz and created four times the amount of flexible, mobile-use spectrum the FCC had licensed to date. In March 2018, European Union lawmakers agreed to open up the 3.6 and 26 GHz bands by 2020.
   The new 5G wireless devices also have 4G LTE capability, as the new networks use 4G for initially establishing the connection with the cell, as well as in locations where 5G access is not available.
  
  5G can support up to a million devices per square kilometer, while 4G supports only up to 100,000 devices per square kilometer.
  
  Section::::Overview.:Usage scenario.
   BULLET::::- In August 2012, New York University founded NYU WIRELESS, a multi-disciplinary academic research centre that has conducted pioneering work in 5G wireless communications.
   BULLET::::- December 2002 – Launched SmarTone iN! – Proprietary advanced multimedia services mobile portal for customers
  
  BULLET::::- August 2012 – Re-farmed the 2G 1800 MHz frequency band for its 4G LTE network and put into use
  
  BULLET::::- September 2014 – Announced in the 2013/2014 Annual Results Announcement that it started to re-farm its 2G 900 MHz spectrum for 4G LTE, to provide even better coverage. The re-farming targets to complete at the end of 2014
  
  Section::::Network Development.:Hong Kong.:3G.
  
  BULLET::::- December 2004 – Launched 3G services
   Section::::Standards.:5G NR.
  
  5G NR (New Radio) is a new air interface developed for the 5G network. It is supposed to be the global standard for the air interface of 3GPP 5G networks.
  
  Section::::Standards.:5G NR.:Pre-standard implementations.
  
  BULLET::::- 5GTF: The 5G network implemented by American carrier Verizon for Fixed Wireless Access in late 2010s uses a pre-standard specification known as 5GTF (Verizon 5G Technical Forum). The 5G service provided to customers in this standard is incompatible with 5G NR. There are plans to upgrade 5GTF to 5G NR "Once [it] meets our strict specifications for our customers," according to Verizon.
   BULLET::::- MiFi DLNA Server: start, stop, and configure the MiFi DLNA server
  
  Section::::Devices.:4G mobile hotspot devices.
  
  The Las Vegas Consumer Electronics Show 2011 saw the introduction of two new 4G-capable MiFi devices from Novatel:
  
  BULLET::::- Verizon Wireless featured the 4510L model, which will connect to Verizon's LTE 4G network, expected to support 5–12 Mbps download and 2–5 Mbit/s upload.
  
  BULLET::::- Sprint featured the MiFi 4082, a WiMAX version.
  
  Both devices maintain backward compatibility with existing 3G networks. Other features include: 
  
  BULLET::::- MiFiOS with widget support
  
  BULLET::::- MicroSD card slot
  
  BULLET::::- GPS receiver
  
  BULLET::::- Four-hour battery life
   Initial 5G NR launches will depend on existing LTE (4G) infrastructure in non-standalone (NSA) mode (5G NR software on LTE radio hardware), before maturation of the standalone (SA) mode (5G NR software on 5G NR radio hardware) with the 5G core network.
   The 600MHz network remains not available commercially as there are no devices available for the NR band n71 (600MHz). However, on July 11, 2019, T-Mobile and Ericsson completed their first n71 (600MHz) data session in their lab in Bellevue, Washington on a commercial 5G modem, the Snapdragon X55, which is the first commercial 5G modem to feature the n71 band. However, the modem is currently pre-market and not in any commercially available device.
  
  Section::::Wireless networks.:Roaming.
  
  T-Mobile has roaming arrangements with a number of national and regional mobile network operators, including AT&T Mobility.
   BULLET::::- In February 2013, ITU-R Working Party 5D (WP 5D) started two study items: (1) Study on IMT Vision for 2020 and beyond, and; (2) Study on future technology trends for terrestrial IMT systems. Both aiming at having a better understanding of future technical aspects of mobile communications towards the definition of the next generation mobile.
   Sprint has announced that on 6 November 2015 the Sprint WiMAX network will be decommissioned effectively removing 4G capabilities on the SPH-D710 model. Users will still have access to data service using the 3G network.
  
  Section::::Variants.:United States.:Sprint - Model SPH-D710.:Boost Mobile and Virgin Mobile USA.
  
  Sprint subsidiaries Boost Mobile offers a Sprint SPH-D710 variant of the Galaxy S II 4G in both titanium grey or white options. Virgin Mobile offers a variant, model i9210, for their service.
   Non-Standalone (NSA) mode of 5G NR refers to an option of 5G NR deployment that depends on the control plane of existing LTE network for control functions, while 5G NR exclusively focused on user plane. The advantage of doing so is reported to speed up 5G adoption, however some operators and vendors have criticized prioritizing the introduction of 5G NR NSA on the grounds that it could hinder the implementation of the standalone mode of the network.
  
  Section::::Deployment modes.:Standalone mode.
   Next Generation Mobile Networks Alliance feel that 5G should be rolled out by 2020 to meet business and consumer demands. In addition to simply providing faster speeds, they predict that 5G networks will also need to meet the needs of new use-cases such as the Internet of things (IoT) as well as broadcast-like services and lifeline communications in times of disaster.
   Likewise, 'WiMAX 2', 802.16m, has been approved by ITU as the IMT Advanced family. WiMAX 2 is designed to be backward compatible with WiMAX 1 devices. Most vendors now support conversion of 'pre-4G', pre-advanced versions and some support software upgrades of base station equipment from 3G.
   The first fairly substantial deployments were in April 2019. In South Korea, SK Telecom claimed 38,000 base stations, KT Corporation 30,000 and LG U Plus 18,000; of which 85% are in six major cities. They are using 3.5 GHz (sub-6) spectrum in non-standalone (NSA) mode and tested speeds were from 193 to 430 Mbit/s down. 260,000 signed up in the first month and the goal is 10% of phones on 5G by the end of 2019.
  
  Nine companies sell 5G radio hardware and 5G systems for carriers: Altiostar, Cisco Systems, Datang Telecom, Ericsson, Huawei, Nokia, Qualcomm, Samsung and ZTE.
  
  Section::::Deployment.:Spectrum.
   BULLET::::- On 1 October 2013, NTT (Nippon Telegraph and Telephone), the same company to launch world's first 5G network in Japan, wins Minister of Internal Affairs and Communications Award at CEATEC for 5G R&D efforts
  
  BULLET::::- On 6 November 2013, Huawei announced plans to invest a minimum of $600 million into R&D for next generation 5G networks capable of speeds 100 times faster than modern LTE networks.
   Section::::Concerns.:Surveillance concerns.
  
  Because of espionage fears on foreign users by Chinese equipment vendors, several countries (including Australia, United Kingdom, Netherlands as of early-2019) have taken actions to restrict or eliminate the use of Chinese equipment in their respective 5G networks. Chinese vendors and the Chinese government have denied these claims.
  
  Section::::Concerns.:Health concerns.
   In 2007, Telus Mobility launched mobile virtual network operator (MVNO) Amp'd Mobile Canada, but replaced it in 2008 with Koodo Mobile
  
  In February 2008, Telus Mobility discontinued its AMPS analog network, and launched its HSPA+ network in November 2009. Telus offered landlines to customers affected by the AMPS network's shutdown in rural areas, as digital signals are less reliable than analog ones in such areas. Following both events, Telus began a slow phasing out of CDMA devices, especially those that support both AMPS and CDMA technologies.
  
  Section::::History.:2010s.
   The ITU-R has defined three main uses for 5G. They are Enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communications (URLLC), and Massive Machine Type Communications (mMTC). Enhanced Mobile Broadband (eMBB) uses 5G as a progression from 4G LTE mobile broadband services, with faster connections, higher throughput, and more capacity. Ultra-Reliable Low-Latency Communications (URLLC) refer to using the network for mission critical applications that requires uninterrupted and robust data exchange. Massive Machine-Type Communications (mMTC) would be used to connect to a large number of low power, low cost devices, which have high scalability and increased battery lifetime, in a wide area. Neither URLLC nor mMTC are expected to be deployed widely before 2021.
  