Non-dialable Point

In conventional landline telephony, a non-dialable toll point or toll station was a lone station or line serving a rural subscriber many miles from the nearest central office. As it had no home telephone exchange and therefore no local calling area, all connections were obtained manually from the long distance operator.

These toll stations were one of multiple categories of non-dialable points which could only be reached with assistance from the inward operator at destination. Other non-dialable points included locations reachable only by some form of two-way radio and specific categories of manual service.

As manual services are replaced by automated infrastructure and satellite telephony now reaches the most distant points on the globe, truly non-dialable points are becoming rare.

Toll stations

To reach remote rural locations, telephone companies have been created with as little as one subscriber (the Methodist Episcopal Corporation, established in the 1940s to interconnect a Methodist church in Carmanville, Ontario to Bell Canada's long-distance network, was taken over by Bell in 1970).

A similar service was provided in North America using toll stations or "ring downs", individual subscribers who were connected over many miles of landline directly to AT&T long distance with no local calling area. Reachable only with operator assistance, these served points like Deep Springs College in Deep Springs, California (whose telephone number for much of the 1980s remained "Deep Springs Toll Station #2"), far corners of the Nevada or California deserts and a few individual ranches in very remote corners of the Texas Panhandle. In Canada, regional incumbent local exchange carriers (such as Telus in Alberta, MTS in Manitoba or Bell Canada in Ontario and Quebec) provided operator assistance to complete inbound calls to non-dialable points.

Local telephone companies were installing toll stations in distant rural areas as recently as the 1970s. While many of these points have subsequently been moved to conventional dial exchanges, in 1999 just over six hundred toll stations were still in service in the North American Numbering Plan. Many were a lone party line serving some remote hamlet too small for its own telephone exchange. In 1999, more than half of the remaining toll stations were in Canada, with Quebec and Newfoundland the largest users. The remaining US toll stations mostly served rural Nevada, with a handful in California and Oregon.

A request for "Tinyville Toll Station #2" would require the operator to call the inbound operator (NPA+121) or a special ringdown operator (NPA+181) at destination, who would ring the one line to "Tinyville" with a specific pattern to signal the second subscriber to answer. The system created operator confusion and was incompatible with equipment based on auto-dial modems, such as automated teller machines. Nevada Bell and GTE replaced the last of their Nevada toll stations with seven-digit dial service in 2001.

These points originally appeared directly in national AT&T or Bellcore routing tables; each would have its own V and H co-ordinates (as toll calls are billed by distance) and a non-dialable number for billing records (initially within the geographic area code, although often in an invalid format like 702-012-3456). The list of non-dialable points was later maintained by NANPA (in the US) and CNAC (in Canada). A pair of area codes (886 and 889), created along with 887 and 888 in the early 1980s and abolished on July 1, 2003, was used by NANPA and CNAC to list each non-dialable toll point as a rate centre and exchange (a block of 10,000 numbers with an associated geographic pair of V/H co-ordinates for billing distance calculation); these codes have since been reclaimed for use as future toll-free numbers.

88X

During the 1980s and into the early 1990s, AT&T maintained eight pseudo-area codes used to represent non-dialable locations. A "ticket" (manual or electronic) would use the six digits as point identification (out of a table) and rating location (using the V and H coordinates), with zeroes or some other representation using the last four digits. Each 88X-XXX combination had its own point name and V and H coordinates.

881, 882, 883 and 885 were used to refer to locations in Mexico that were not able to be direct dialed; these gradually disappeared as Mexico tied them into its dialing network, becoming a 52X (1 through 9) prefix instead. 88X-XXX would be followed by up to four digits of a local number.

886, 887, 888 and 889 were used to refer to assorted types of locations in Canada and the United States. Where the six-digit combination represented a radio telephone base station, the remaining four digits usually were used to give the last four digits of the radio telephone number. Where the six-digit combination represented a toll station as described above, the last four digits were all zeroes or might represent a specific subscriber sharing the same toll station. These codes were eventually eliminated by need of using the digits for other services, as unlike the ones used for Mexico, their phase-out was far slower.

Manual exchanges

Long after the introduction of local dial service to major cities in the 1920s, 1930s, and 1940s, and the creation of the original 86 North American area codes in 1947, calls to tiny, out-of-the way places required time-consuming setup by multiple manual operators at various intermediate points. As one of many examples, a call from a police sergeant in Los Angeles to a three-digit number in Murphy, Idaho

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