Mobile Telephone Service
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The Mobile Telephone Service (MTS) is a pre-cellular VHF radio system that links to the PSTN. MTS was the radiotelephone equivalent of land dial phone service. As of 2005, only rural and wilderness areas are still using the system.
[edit] Channels
MTS uses 25 VHF radio channels in the United States and Canada. The channels are identified by pairs of letters taken from positions on a North American telephone dial that, when changed to digits, form (for 12-channel mobile sets) 55, 57, 95 and 97.
| 12-Channel Mobile |
Ident | 24-Channel Mobile |
Base Station MHz | |
|---|---|---|---|---|
| Transmit | Receive | |||
| JJ | 152.480 | 157.740 | ||
| XJ | 1 | 152.495 | 157.755 | |
| 1 | JL | 2 | 152.510 | 157.770 |
| XK | 3 | 152.525 | 157.785 | |
| 2 | YL | 4 | 152.540 | 157.800 |
| XL | 5 | 152.555 | 157.815 | |
| 3 | JP | 6 | 152.570 | 157.830 |
| XP | 7 | 152.585 | 157.845 | |
| 4 | JJ | 8 | 152.600 | 157.860 |
| XR | 9 | 152.615 | 157.875 | |
| 5 | YJ | 10 | 152.630 | 157.890 |
| XS | 11 | 152.645 | 157.905 | |
| 6 | YK | 12 | 152.660 | 157.920 |
| XT | 13 | 152.675 | 157.935 | |
| 7 | JS | 14 | 152.690 | 157.950 |
| XU | 15 | 152.705 | 157.965 | |
| 8 | YS | 16 | 152.720 | 157.980 |
| XV | 17 | 152.735 | 157.995 | |
| 9 | YR | 18 | 152.750 | 158.010 |
| XW | 19 | 152.765 | 158.025 | |
| 10 | JK | 20 | 152.780 | 158.040 |
| XX | 21 | 152.795 | 158.055 | |
| 11 | JR | 22 | 152.810 | 158.070 |
| XY | 23 | 152.825 | 158.085 | |
| 12 | JW | 24 | 152.840 | 158.100 |
[edit] Frequency problems and elimination of the service
These channels are prone to network congestion and interference since a radio closer to the terminal will sometimes take over the channel due to having a more powerful signal. The service uses technology that has, for at least three decades, not been manufactured ("manufacturer discontinued").
The driver for replacement in most of North America, particularly large cities, was the congestion, i.e., the inability of the network to carry more than two dozen channels in a geographic area. Cellular service resolved this congestion problem very effectively, especially since cellular frequencies, typically UHF, do not reach as far as VHF frequencies and can therefore be reused. The ability of a cellular system to use signal strength to choose channels and split cells into smaller units also helps expand channel capacity.
The driver for replacement in remote areas, however, is not network congestion, but obsolescence. Because the equipment is no longer manufactured, companies still using the service must struggle to keep their equipment operating, either by cannibalizing from retired equipment or improvising solutions. As there is insufficient traffic, cellular is not a cost-effective replacement. The only viable solution is satellite telephony, as the small number of "base stations" orbit the planet serving large geographic regions as they pass over. Cost, however, has been an issue, and the replacement will become acceptable to VHF mobile customers gradually, as the cost of satellite has been dropping and will continue to drop.
Many MTS frequencies are now used for local paging services. They are only found in some parts of rural North America, having been replaced in most areas by cellular service in the 1980s and later.
The service territory of Northwestel has only eliminated ten MTS locations since 2003; in the case of six sites, cellular is available and the company had to rent tower space for five sites, making them even more unprofitable; four other sites had virtually nil traffic. The remainder of the MTS network is still operating, though at a deficit, virtually blanketing the Yukon and northern British Columbia highway network, the western Great Slave Lake region, the Mackenzie River and the Mackenzie Delta. As noted above, cellular service is too costly to install in these areas due to a more limited signal reach, cellular sites are more complex technology, and they would still require the same logistical support (electricity supply from diesel generators, using barged-in fuel).
[edit] See also
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