ThePersonal Handy-phone System (PHS), also known as thePersonal Communication Telephone (PCT) in Thailand, and thePersonal Access System (PAS) and commercially branded asXiaolingtong (Chinese:小灵通) inChina, was amobile network system operating in the 1880–1930MHz frequency band. InJapan, it was introduced as a low-cost wireless service with smaller coverage areas than standard cellular networks. Its affordability made it popular in China,Taiwan, and other parts ofAsia, as both the handsets and network infrastructure were relatively inexpensive to maintain.[1]
Developed in the 1990s, PHS used amicrocell architecture with low-power base stations covering 100 to 500 metres (330 to 1,640 ft). Unlike conventionalcellular networks that relied on large cell sites for extensive coverage, PHS’s design was better suited for dense urban environments and reduced infrastructure costs.
PHS was overtaken in the marketplace byGSM (2G) andUMTS (3G), with the last retail network decommissioned in 2021 and the last commercial network terminated in 2023.[2]
PHS is essentially acordless telephone likeDECT, with the capability tohandover from onecell to another. PHS cells are small, with transmission power ofbase station a maximum of 500 mW and range typically measures in tens or at most hundreds of metres (some can range up to about 2 kilometres in line-of-sight), contrary to the multi-kilometre ranges ofCDMA andGSM. This makes PHS suitable for dense urban areas, but impractical for rural areas, and the small cell size also makes it difficult if not impossible to make calls from rapidly moving vehicles.
PHS usesTDMA/TDD for its radiochannel access method, and 32 kbit/sADPCM for its voicecodec. Modern PHS phone can also support manyvalue-added services such as high speed wirelessdata/Internet connection (64 kbit/s and higher),WWW access,e-mailing, and text messaging.
PHS technology is also a popular option for providing awireless local loop, where it is used for bridging the "last mile" gap between thePOTS network and the subscriber's home. It was developed under the concept of providing a wirelessfront-end of anISDN network. Thus a PHS base station is compatible with ISDN and is often connected directly to ISDNtelephone exchange equipment e.g. a digital switch.
In spite of its low-costbase station,micro-cellular system and "Dynamic Cell Assignment" system, PHS offers higher number-of-digits frequency use efficiency with lower cost (throughput per area basis), compared with typical3Gcellular telephone systems. It enables flat-rate wireless service such asAIR-EDGE, throughout Japan.
The speed of an AIR-EDGE data connection is accelerated by combining lines, each of which basically is 32 kbit/s. The first version of AIR-EDGE, introduced in 2001, provided 32 kbit/s service. In 2002, 128 kbit/s service (AIR-EDGE 4×) started and in 2005, 256 kbit/s (8×) service started. In 2006, the speed of each line was also upgraded to 1.6 times with the introduction of "W-OAM" technology. The speed of AIR-EDGE 8× is up to 402 kbit/s with the latest "W-OAM" capable instrument.
In April 2007, "W-OAM typeG" was introduced allowing data speeds of 512 kbit/s for AIR-EDGE 8x users. Furthermore, the "W-OAM typeG" 8× service was planned to be upgraded to a maximum throughput of 800 kbit/s, when the upgrading for access points (mainly switching lines from ISDN tofibre optic) in its system are completed. Thus it was expected to exceed the speeds of popularW-CDMA 3G service likeNTT DoCoMo'sFOMA in Japan.
Developed byNTT Laboratory in Japan in 1989 and far simpler to implement and deploy than competing systems likePDC orGSM, the commercial services were started by three PHS operators (NTT-Personal, DDI-Pocket, and ASTEL) in Japan in 1995, forming the PIAF (PHS Internet Access Forum). However, the service was pejoratively dubbed as the "poor man's cellular", due to its limited range and roaming abilities. NTT DoCoMo, which absorbed NTT Personal, and ASTEL terminated the PHS service in January 2008.
In Thailand, TelecomAsia (nowTrue Corporation) integrated the PHS system withIntelligent Network and marketed the service as Personal Communication Telephone (PCT).[3] The integrated system was the world's first that allowed thefixed line telephone subscribers of thepublic switched telephone network to use PHS as a value added service with the same telephone number and shared the same voice mailbox.[4][5] The PCT service was commercially launched in November 1999 with the peak of 670,000 subscribers in 2001. However, the number of subscribers had declined to 470,000 in 2005 before the breakeven in 2006 after six years of heavy investment up to 15 billion THB. With the popularity of other cellular phone services, the company shifted the focus of the PCT to a niche market segment of youths ages 10-18.[6]
Wireless local loop (WLL) systems based on PHS technology are in use in some of the above-mentioned countries.WILLCOM, formerly DDI-Pocket, introduced flat-ratewireless network and flat-rate calling in Japan, which reversed the local fate of PHS up to an extent. In China, there was an explosive expansion of subscribers until around 2005. In Chile,Telefónica del Sur launched a PHS-based telephony service in some cities of the southern part of the country in March 2006. In Brazil,Suporte Tecnologia has a PHS-based telephony service inBetim, state of Minas Gerais[needs update], andTransit Telecom announced a rollout of a PHS network in 2007[needs update].
China Telecom operated a PAS system in China, although technically it was not regarded as allowed to provide mobile services, because of some particularities of the Chinese governance.China Netcom, the other fixed-line operator in China, also provides Xiaolingtong service. The system was a runaway hit, with over 90 million subscribers signed up as of 2007[update]; the largest equipment vendors wereUTStarcom andZTE. However, low priced mobile phones rapidly replaced PHS. TheMinistry of Industry and Information Technology of the People's Republic of China issued notices on 13 February 2009 that both registration of new users and expansion of the network were to be discontinued, with the service to be ended by the end of 2011.[7]
A PHS global roaming service was available between Japan (WILLCOM), Taiwan, and Thailand.
This is a list of commercial PHS deployments around the world, all of which are now defunct:[8]
| Country | Operator | f (MHz) | Launch date | End of service | Notes |
|---|---|---|---|---|---|
 Japan | NTT DoCoMo | 1884,65–1919,45 | Jul 1995 | Jan 2008 | [9][10][11][12][13][14] |
| Japan | Softbank (Y!mobile) | 1884,65 - 1919,45 | Jul 1995 | Jan 2021 (retail) Apr 2023 (commercial)[2] | [9][15][16][17][18][19][20][21][22][23][24] Willcom merged witheAccess intoY!mobile in 2014. Operated by Carlyle (Willcom) (2004–2010). Operated byKDDI (DDI Pocket) (1995–2004). 070 prefix under theJapanese telephone numbering plan. |
 Hong Kong | 1895–1906,1 | 1997 | May 2016 | [25][26][27][28] | |
 China | China Unicom China Telecom (Xiaolingtong) (Little Smart) | 1880–1920 | 1998 | Sep 2013 | [29][30] |
 Thailand | True Corporation | 1906,1 - 1918,1 | Nov 1999 | 2013 | [31][32][4] Additional service for fixed-line subscribers. |
 Taiwan | Fitel | 1905–1915 | May 2001 | Mar 2015 | [33][34][35][36][37][38] |
 Chile | Telefónica del Sur | 1910–1930 | Mar 2006 | May 2011 | [39][40] |
PHS-enabledPCMCIA/CompactFlash cards include:
Cellular network standards | |||||||||
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| 0Gradio telephones (1946) | |||||||||
| 1G (1979) |
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| 2G (1991) |
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| 2G transitional (2.5G, 2.75G, 2.9G) |
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| 3G (1998) IMT-2000 (2001) |
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| 3G transitional (3.5G, 3.75G, 3.9G) |
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| 4G (2009) IMT Advanced (2013) |
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| 5G (2018) IMT-2020 (2021) |
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| Related articles | |||||||||
