142:
users. In this way a single base station with a number of different channels can be run by one operator for a number of different users and this makes efficient use of the base station equipment. The base station site can also be located at a position that will give optimum radio coverage, and private lines can be provided to connect the users control office to the transmitter site. As there is no incremental cost for the transmissions that are made, individual calls are not charged, but instead there is a rental for overall use of the system. For those users with their own licences they naturally have to pay for the licence and the cost of purchase and maintenance of that equipment.
323:
mechanisms, aimed at limiting the load on the control channel caused by mobiles roaming. Registrations may be explicit or implicit. An explicit registration may be initiated by the control channel demanding that a mobile issues a registration request; or initiated by a mobile which has roamed to a new registration area. It is also possible for a mobile to implicitly register, where the TSC will update its registration records when the mobile makes a call attempt. It is possible that the TSC's record does not match the mobile's location. This can occur, for example, where a mobile is switched off and then moved within coverage of a different site.
343:
group; or it may be random access. Random access timeslots will be used when a mobile user initiates a call, or when a mobile registers on the TSC. On a heavily loaded control channel, it is likely that two or more mobile radio units will try to transmit at the same time on the same random access timeslot. This is detected by mobile, when the expected reply from the TSC is not received within a certain timeout. The mobile may then retry its request in another random access slot. The timeouts and number of retries is configured in the mobile when it is set up for the network.
235:(CTCSS) also referred to as subaudible tones or PL tones (a Motorola trademark). This uses single audio tones in the range from 67 to 257 Hz to address each message to a specific radio or a group (or fleet) of radios. Each radio or group is assigned a different tone frequency. The code tone is transmitted continuously throughout the audio transmission along with the voice modulation. Since the tones are below the audio passband of the receiver, roughly 300–3,000 Hz, they are filtered out in the receiver's audio amplifier and therefore not heard.
162:. Typically a deviation of 2.5 kHz is used for FM and this enables a channel spacing of 12.5 kHz to be implemented. As the demands for PMR are high, it is necessary to make effective use of the channels available. This is achieved by re-using the frequencies in different areas. Base stations must be located sufficiently far apart so that interference is not experienced, and also selective calling techniques such as CTCSS and DTMF are used to ensure that as many mobiles as possible can use a given channel.
303:
additional facilities. In view of the very high cost of setting up trunked networks, they are normally run by large leasing companies or consortia that provide a service to a large number of users. In view of the wider areas covered by these networks and the greater complexity, equipment has to be standardised so that suppliers can manufacture in higher volumes and thereby reduce costs to acceptable levels. Most trunked radio systems follow the MPT1327 format.
347:
mentioned the second type of word is the address codeword. It is the first codeword of any message and it defines the nature of the message. It is possible to send data over the control channel. When this occurs, both the CSCC and the address codewords are displaced with the data appended to the address codeword. The mobile radio unit data structure is somewhat simpler. It consists fundamentally of synchronism bits followed by the address codeword.
1924:
1934:
20:
1913:
1944:
272:
450–470 MHz, 385–390 MHz / 395–399.9 MHz, have been allocated for TETRA. Then for the emergency services in Europe the frequency bands 380–383 MHz and 390–393 MHz have been allocated. In addition to this, the whole or appropriate parts of the bands between 383–385 MHz and 393–395 MHz can be utilized.
204:. The eight audio frequencies used in DTMF are 697, 770, 852, 941 Hz which are called the "low tones" and 1,209; 1,336; 1,477; and 1,633 Hz which are the "high tones". Pairs of one high and one low tone transmitted together represent a decimal number. Each station is assigned a unique DTMF
379:
Although the data is transmitted as digital information, the audio or voice channels for the system are analogue, employing FM. However some work has been carried out to develop completely digital systems. The main systems are by
Motorola, by Ericsson (EDACS) and Johnson (LTR). These systems have not
271:
TETRA allocates the channels to users on demand in both voice and data modes. Additionally national and multi-national networks are available and national and international roaming can be supported. For civil systems in Europe the frequency bands 410–430 MHz, 870–876 MHz / 915–921 MHz,
267:
cellular radio standard, as well as experience from the development and use of trunked radio systems has also been used to fashion the TETRA standard. In addition to this the process has gained from the co-operation of manufacturers, users, operators and industry experts. With this combined expertise
146:
446.196875 MHz. These are used for personal or business communications where they are legal. Split frequency repeaters are not allowed on these frequencies and these radios do not communicate with licensed PMR systems. PMR446 radios are much cheaper than those used for the licensed PMR systems.
342:
where the forward or downlink channel (that received by the mobiles) provides timeslots within which a mobile may transmit a request in the uplink channel. In general, a mobile may only transmit on the control channel if invited to by TSC. This invitation may be explicitly addressed to a mobile or a
334:
There is no method described within the standard to "handover" the mobile from one base station to the next if it moves out of range of the base station through which a call is being made. In this way the system is not a form of cellular telephone. It is therefore necessary for the mobile station to
346:
Signalling on the forward control channel is nominally continuous with each slot comprising 64 bit code words. The first type is the
Control Channel System Codeword (CSCC). This identifies the system to the mobile radio units and also provides synchronization for the following address codeword. As
314:
A number of different control channels are used so that adjacent base stations do not interfere with one another, and the mobile stations scan the different channels to locate the strongest control channel signal. In addition to this there are the traffic channels. The specification supports up to
145:
The term PMR is often used by the public and magazine publishing to refer to the low power (500 milliwatt) PMR446 license exempt radio systems that consist of sixteen FM frequencies between 446.00625 and 446.19375 MHz for analog FM and thirty-two FDMA (digital) channels between 446.003125 and
141:
Licenses are allocated for operation on a particular channel or channels. The user can then have use of these channels to contact the mobile stations in their fleet. The base station may be run by the user themselves or it may be run by an operating company who will hire out channels to individual
326:
To make an outgoing call the mobile transmits a request to the base station as requested in the control channel data stream from the base station. The mobile transmits its own code along with that of the destination of the call, either another mobile or a control office. The control software and
322:
For successful operation it is essential that the system knows where the mobiles are located so that calls can be routed through to them. The TSC (Trunking System
Controller) gains this information by mobiles "registering" on a control channel. The MPT1327 standard describes several registration
302:
A trunked version of the private mobile radio (PMR) concept that is defined under the standard MPT 1327 (MPT1327) is widely used and provides significant advantages over the simpler single station systems that are in use. MPT1327 enables stations to communicate over wider areas as well as having
242:
for that receiver (or group) be opened and the transmitted audio be heard. The advantage of this system is that the code tone is transmitted during the entire transmission, instead of just at the beginning as in the DTMF system above, so the system works in spite of noise or signal dropouts.
176:
The simplest systems operate with all the radios on a frequency channel being able to hear all the calls being made. In some applications this may not be desirable and a system of selective calling may be required, in which two radios on a channel can have a private conversation which is not
310:
In order to be able to carry the audio information and also run the variety of organisational tasks that are needed the system requires different types of channel to be available. These are the control channels of which there is one in each direction for each base station or
Trunking System
315:
1,024 different traffic channels to be used. In this way a base station can support a large number of different mobile stations that are communicating at the same time. However, for small systems with only a few channels, the control channel may also act as a non-dedicated traffic channel.
125:
When private- or professional-mobile-radio (PMR) first started the systems simply consisted of a single base station with a number of mobiles that could communicate with this single base station. These systems are still in widespread use today with taxi firms and many others using them for
216:
A disadvantage of this system is that since the DTMF code is sent only once at the beginning of a message, if the receiver does not pick up the code due to temporary noise or bad signal conditions the receiver will not turn on and it will miss the entire message. This can be a significant
327:
circuitry within the base station and the central control processing area for the network sets up the network so that a channel is allocated for the audio (the traffic channel). It also sets up the switching in the network to route the call to the required destination.
306:
To implement trunked PMR a network of stations is set up. These stations are linked generally using land lines, although optical fibers and point to point radio are also used. In this way the different base stations are able to communicate with each other.
212:
circuit in each radio decodes the tones and turns the receiver audio on if the transmission is addressed to that radio. There is also a code for "broadcast" transmissions, which causes the transmission to be received by all the radios on the channel.
177:
received by the others, or in which a specific radio can be promptly contacted and made to "ring" almost like an ordinary phone. Two widely used systems are Dual Tone
Multiple Frequency (DTMF), and Continuous Tone Coded Squelch System (CTCSS).
191:
A DTMF selective signaling PMRS system uses a code sequence of discrete audible tones, representing numbers, transmitted at the beginning of each voice message to address the transmission to a specific station or group of stations. The DTMF
330:
To enable the mobile station to receive a call, it is paged via the incoming control channel data stream to indicate that there is an incoming call. Channels are allocated and switching set up to provide the correct routing for the call.
360:"Ahoy" messages — Sent by the base station to demand a response from a particular radio unit. This may be sent to request the radio unit to send his unique identifier to ensure it should be taking traffic through the base station.
318:
The control channels use signalling at 1,200 bits per second with fast frequency shift keying (FFSK) subcarrier modulation. It is designed for use by two-frequency half duplex mobile radio units and a full duplex TSC.
403:
263:
Work started on the development of the TETRA standards in 1990 and has relied on the support of the
European Commission and the ETSI members. Experience gained in the development of the
243:
Systems typically are able to provide from 32 to 50 different tones between 67 Hz and 254.1 Hz, allowing multiple separately addressable radios or groups of radios.
138:
may be mounted on a high tower, coverage may extend up to distances of fifty kilometres. This is helpful especially when there is no signal in a GSM mobile phone.
1968:
1896:
1868:
1863:
888:
101:, in which multiple radios share a common radio channel, and only one can transmit at a time. Transceivers are normally in receive mode, the user presses a
113:
bands, giving them a limited range, usually 3 to 20 miles (4.8 to 32 km) depending on terrain. Output power is typically limited to 4 watts.
1973:
492:
1890:
1885:
1875:
1855:
1657:
732:
232:
226:
1880:
1726:
742:
1652:
417:
105:
button on his microphone when he wants to talk, which turns on his transmitter and turns off his receiver. They use channels in the
1746:
795:
603:
201:
1531:
1079:
881:
1642:
366:
Go to channel messages — These messages instruct a particular mobile radio unit to move to the allocated traffic channel.
1637:
1188:
1662:
712:
280:
1947:
363:
Acknowledgments — These are sent by both the base stations and the mobile radio units to acknowledge the data sent.
1937:
1698:
1595:
1138:
905:
593:
540:
350:
There are a number of different types of control channel messages that can be sent by the base station to the mobiles:
268:
the first standards were ready in 1995 to enable manufacturers to design their equipment to interoperate successfully.
1927:
1434:
874:
608:
485:
1786:
1708:
1647:
1354:
800:
1558:
1519:
1364:
1264:
1193:
1126:
953:
825:
618:
434:
252:
450:
1917:
1159:
1094:
1047:
933:
850:
666:
1756:
1741:
1585:
1536:
1459:
1359:
1037:
923:
918:
810:
560:
1678:
1464:
1279:
1224:
1219:
1032:
997:
520:
478:
283:(TDMA) technology with four user channels on one radio carrier with 25 kHz spacing between carriers.
1580:
1384:
1349:
1269:
1249:
1171:
1059:
980:
555:
217:
disadvantage because mobile stations often lose the signal for short periods as they are on the move.
1494:
1454:
1424:
1181:
1116:
1007:
820:
671:
535:
530:
159:
70:
54:
1504:
1444:
1203:
1165:
1022:
963:
948:
855:
702:
588:
525:
372:
Short data messages — These may be sent by either the base station or the mobile radio unit.
260:
is a modern standard for digital private mobile radio (PMR) and public access mobile radio (PAMR).
110:
106:
354:
Aloha messages — Sent by the base station to invite and mobile stations to access the system
1731:
1688:
1619:
1489:
1419:
1394:
1329:
1176:
897:
455:
117:
installed on tall buildings, hills or mountain peaks are used to increase the range of systems.
1771:
1693:
1607:
1590:
1553:
1439:
1399:
1229:
1198:
1064:
958:
762:
757:
722:
171:
1776:
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1612:
1570:
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1339:
1324:
1299:
1274:
1234:
1084:
943:
938:
928:
707:
404:"Thales launches Every Talk, the first ruggedized high-speed smartphone for security forces"
94:
335:
remain within the service area of the base station through which any calls are being made.
275:
Low speed packet data as well as circuit data modes are available, along with some form of
1404:
1259:
1027:
990:
840:
790:
135:
1002:
1602:
1474:
1449:
1409:
1379:
1254:
1089:
975:
661:
1962:
1751:
1524:
1514:
1429:
1319:
1314:
1304:
1289:
1111:
970:
676:
646:
515:
501:
339:
73:
which are designed for dedicated use by specific organizations, or standards such as
46:
42:
1629:
1469:
1414:
1344:
1309:
1244:
1143:
1133:
985:
815:
752:
651:
641:
102:
82:
50:
1829:
1479:
1389:
1374:
1334:
1294:
1153:
845:
835:
830:
375:
Miscellaneous messages — Sent by the base station for control applications
98:
1834:
1541:
1239:
1148:
1104:
1074:
1052:
1042:
1017:
465:
439:
369:
Single address messages — These are sent only by the mobile radio units.
287:
276:
197:
155:
66:
19:
1819:
1284:
1099:
805:
238:
Only when the correct tone for the required station is transmitted will the
86:
1814:
1804:
1721:
1546:
1369:
747:
692:
613:
384:
205:
114:
58:
23:
1809:
1794:
767:
697:
598:
545:
239:
209:
1839:
1799:
1121:
913:
866:
772:
737:
623:
570:
565:
550:
279:. The systems makes use of the available frequency allocations using
78:
357:
Requests — Sent by radio units to request a call to be set up
1824:
1761:
1069:
291:
131:
62:
18:
1766:
470:
193:
186:
158:
is the chosen form of modulation, although airport services use
127:
90:
77:
intended for general commercial use. These systems are used by
74:
870:
474:
1012:
264:
444:
57:
console radios. PMR systems are based on such standards as
89:, and emergency services, and by commercial firms such as
460:
1848:
1785:
1707:
1671:
1628:
1569:
1503:
1212:
904:
781:
721:
685:
632:
579:
508:
466:
Watch Video impression from PMRExpo 2011 exhibition
196:) code is used, which is also universally used for
418:"Thales lance Every Talk, smartphone 'haut débit'"
134:provide additional calling selection. Because the
882:
486:
8:
1897:Global telecommunications regulation bodies
1933:
889:
875:
867:
493:
479:
471:
395:
45:voice communications systems which use
208:, consisting of several numbers. The
126:communication. Now facilities such as
447:Collection of mainly UK PMR equipment
7:
1943:
294:network was launched on 26 May 2011
233:Continuous Tone-Coded Squelch System
227:Continuous Tone-Coded Squelch System
1969:Mobile telecommunications standards
440:The Pye Telecom Historic Collection
380:gained such widespread acceptance.
456:PMR System Integration by T.E.S.S.
338:The control channel discipline is
231:Another widely used system is the
41:) in the UK) are person-to-person
16:Field radio communications systems
14:
604:Common traffic advisory frequency
154:In general narrow band frequency
1942:
1932:
1923:
1922:
1911:
1532:Free-space optical communication
286:The first ruggedized high-speed
1974:Mobile radio telephone systems
26:HT1000 hand-held two-way radio
1:
713:Maritime mobile amateur radio
281:time-division multiple access
1918:Telecommunication portal
1699:Telecommunications equipment
856:Voting (diversity combining)
594:Aircraft emergency frequency
541:General Mobile Radio Service
1435:Alexander Stepanovich Popov
609:Mandatory frequency airport
1990:
1139:Telecommunications history
801:Automatic vehicle location
382:
298:PMR trunking using MPT1327
250:
224:
184:
169:
1906:
1747:Public Switched Telephone
1559:telecommunication circuit
1520:Fiber-optic communication
1265:Francis Blake (telephone)
1060:Optical telecommunication
826:Dynamic range compression
743:Dual-tone multi-frequency
657:Professional mobile radio
619:Single Frequency Approach
253:Terrestrial Trunked Radio
200:dialing in the worldwide
31:Professional mobile radio
1658:Orbital angular-momentum
1095:Satellite communications
934:Communications satellite
851:Radiotelephony procedure
667:Specialized Mobile Radio
435:Network interoperability
202:public telephone network
194:dual tone multifrequency
1537:Molecular communication
1360:Gardiner Greene Hubbard
1189:Undersea telegraph line
924:Cable protection system
561:Multi-Use Radio Service
1679:Communication protocol
1465:Charles Sumner Tainter
1280:Walter Houser Brattain
1225:Edwin Howard Armstrong
1033:Information revolution
633:Land-based commercial
521:Amateur radio repeater
27:
1653:Polarization-division
1385:Narinder Singh Kapany
1350:Erna Schneider Hoover
1270:Jagadish Chandra Bose
1250:Alexander Graham Bell
981:online video platform
635:and government mobile
582:(aeronautical mobile)
383:Further information:
22:
1495:Vladimir K. Zworykin
1455:Almon Brown Strowger
1425:Charles Grafton Page
1080:Prepaid mobile phone
1008:Electrical telegraph
672:Trunked radio system
536:Public Radio Service
531:Family Radio Service
509:Amateur and hobbyist
160:amplitude modulation
97:. Most systems are
35:private mobile radio
1445:Johann Philipp Reis
1204:Wireless revolution
1166:The Telephone Cases
1023:Hydraulic telegraph
703:Coast radio station
589:Air traffic control
526:Citizens band radio
1643:Frequency-division
1620:Telephone exchange
1490:Charles Wheatstone
1420:Jun-ichi Nishizawa
1395:Innocenzo Manzetti
1330:Reginald Fessenden
1065:Optical telegraphy
898:Telecommunications
686:Marine (shipboard)
571:UHF CB (Australia)
311:Controller (TSC).
28:
1956:
1955:
1694:Store and forward
1689:Data transmission
1603:Network switching
1554:Transmission line
1400:Guglielmo Marconi
1365:Internet pioneers
1230:Mohamed M. Atalla
1199:Whistled language
864:
863:
725:Selective calling
172:Selective calling
166:Selective calling
95:delivery services
1981:
1946:
1945:
1936:
1935:
1926:
1925:
1916:
1915:
1914:
1787:Notable networks
1777:Wireless network
1717:Cellular network
1709:Types of network
1684:Computer network
1571:Network topology
1485:Thomas A. Watson
1340:Oliver Heaviside
1325:Philo Farnsworth
1300:Daniel Davis Jr.
1275:Charles Bourseul
1235:John Logie Baird
944:Data compression
939:Computer network
891:
884:
877:
868:
782:System elements
708:Marine VHF radio
495:
488:
481:
472:
451:MPT1327 standard
422:
421:
414:
408:
407:
400:
1989:
1988:
1984:
1983:
1982:
1980:
1979:
1978:
1959:
1958:
1957:
1952:
1912:
1910:
1902:
1844:
1781:
1703:
1667:
1624:
1573:
1565:
1506:
1499:
1405:Robert Metcalfe
1260:Tim Berners-Lee
1208:
1028:Information Age
900:
895:
865:
860:
841:Rayleigh fading
783:
777:
724:
717:
681:
634:
628:
581:
575:
504:
499:
461:TETRA in Poland
431:
426:
425:
416:
415:
411:
402:
401:
397:
392:
387:
300:
255:
249:
229:
223:
189:
183:
174:
168:
152:
123:
33:(also known as
17:
12:
11:
5:
1987:
1985:
1977:
1976:
1971:
1961:
1960:
1954:
1953:
1951:
1950:
1940:
1930:
1920:
1907:
1904:
1903:
1901:
1900:
1893:
1888:
1883:
1878:
1873:
1872:
1871:
1866:
1858:
1852:
1850:
1846:
1845:
1843:
1842:
1837:
1832:
1827:
1822:
1817:
1812:
1807:
1802:
1797:
1791:
1789:
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1779:
1774:
1769:
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1754:
1749:
1744:
1739:
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1729:
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1713:
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1704:
1702:
1701:
1696:
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1681:
1675:
1673:
1669:
1668:
1666:
1665:
1660:
1655:
1650:
1645:
1640:
1638:Space-division
1634:
1632:
1626:
1625:
1623:
1622:
1617:
1616:
1615:
1610:
1600:
1599:
1598:
1588:
1583:
1577:
1575:
1567:
1566:
1564:
1563:
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1561:
1551:
1550:
1549:
1539:
1534:
1529:
1528:
1527:
1517:
1511:
1509:
1501:
1500:
1498:
1497:
1492:
1487:
1482:
1477:
1475:Camille Tissot
1472:
1467:
1462:
1457:
1452:
1450:Claude Shannon
1447:
1442:
1440:Tivadar Puskás
1437:
1432:
1427:
1422:
1417:
1412:
1410:Antonio Meucci
1407:
1402:
1397:
1392:
1387:
1382:
1380:Charles K. Kao
1377:
1372:
1367:
1362:
1357:
1355:Harold Hopkins
1352:
1347:
1342:
1337:
1332:
1327:
1322:
1317:
1312:
1307:
1302:
1297:
1292:
1287:
1282:
1277:
1272:
1267:
1262:
1257:
1255:Emile Berliner
1252:
1247:
1242:
1237:
1232:
1227:
1222:
1216:
1214:
1210:
1209:
1207:
1206:
1201:
1196:
1194:Videotelephony
1191:
1186:
1185:
1184:
1179:
1169:
1162:
1157:
1151:
1146:
1141:
1136:
1131:
1130:
1129:
1124:
1119:
1109:
1108:
1107:
1097:
1092:
1090:Radiotelephone
1087:
1082:
1077:
1072:
1067:
1062:
1057:
1056:
1055:
1045:
1040:
1035:
1030:
1025:
1020:
1015:
1010:
1005:
1000:
995:
994:
993:
988:
983:
978:
976:Internet video
968:
967:
966:
961:
956:
951:
941:
936:
931:
926:
921:
916:
910:
908:
902:
901:
896:
894:
893:
886:
879:
871:
862:
861:
859:
858:
853:
848:
843:
838:
833:
828:
823:
818:
813:
808:
803:
798:
793:
787:
785:
784:and principles
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445:The Pye Museum
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429:External links
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43:two-way radio
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1630:Multiplexing
1505:Transmission
1470:Nikola Tesla
1460:Henry Sutton
1415:Samuel Morse
1345:Robert Hooke
1310:Amos Dolbear
1245:John Bardeen
1164:
1144:Telautograph
1048:Mobile phone
1003:Edholm's law
986:social media
919:Broadcasting
763:Quik-Call II
753:Push-to-talk
723:Signaling /
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652:Mobile radio
642:Base station
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121:Introduction
103:push-to-talk
51:base station
38:
34:
30:
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1830:NPL network
1542:Radio waves
1480:Alfred Vail
1390:Hedy Lamarr
1375:Dawon Kahng
1335:Elisha Gray
1295:Yogen Dalal
1220:Nasir Ahmed
1154:Teleprinter
1018:Heliographs
846:Tone remote
836:Link budget
831:Fade margin
758:Quik-Call I
99:half-duplex
1963:Categories
1876:Antarctica
1835:Toasternet
1757:Television
1240:Paul Baran
1172:Television
1156:(teletype)
1149:Telegraphy
1127:transistor
1105:Phryctoria
1075:Photophone
1053:Smartphone
1043:Mass media
556:Mobile rig
390:References
288:smartphone
277:encryption
198:touch-tone
156:modulation
150:Modulation
49:, mobile,
1860:Americas
1849:Locations
1820:Internet2
1581:Bandwidth
1285:Vint Cerf
1182:streaming
1160:Telephone
1100:Semaphore
991:streaming
816:DC remote
806:Call sign
580:Aviation
115:Repeaters
87:ambulance
1928:Category
1815:Internet
1805:CYCLADES
1722:Ethernet
1672:Concepts
1596:terminal
1547:wireless
1370:Bob Kahn
1213:Pioneers
1038:Internet
929:Cable TV
821:Dispatch
748:MDC-1200
693:2182 kHz
614:MULTICOM
385:SmartPTT
206:callsign
59:MPT-1327
55:dispatch
47:portable
24:Motorola
1948:Commons
1938:Outline
1891:Oceania
1810:FidoNet
1795:ARPANET
1608:circuit
1177:digital
906:History
791:Antenna
768:Selcall
698:500 kHz
599:Airband
546:KDR 444
240:squelch
210:squelch
136:antenna
67:APCO 25
1886:Europe
1856:Africa
1840:Usenet
1800:BITNET
1737:Mobile
1613:packet
1122:MOSFET
1117:device
914:Beacon
773:SELCAL
738:D-STAR
624:UNICOM
566:PMR446
551:LPD433
79:police
69:, and
53:, and
1869:South
1864:North
1825:JANET
1762:Telex
1752:Radio
1591:Nodes
1586:Links
1507:media
1085:Radio
1070:Pager
998:Drums
964:video
959:image
949:audio
733:CTCSS
292:TETRA
258:TETRA
247:TETRA
221:CTCSS
132:CTCSS
91:taxis
63:TETRA
1881:Asia
1767:UUCP
1727:ISDN
796:APRS
187:DTMF
181:DTMF
130:and
128:DTMF
109:and
93:and
83:fire
75:NXDN
1772:WAN
1742:NGN
1732:LAN
1013:Fax
954:DCT
811:CAD
265:GSM
111:UHF
107:VHF
71:DMR
39:PMR
1965::
85:,
81:,
65:,
61:,
1899:)
1895:(
890:e
883:t
876:v
494:e
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480:v
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192:(
37:(
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