Telephone Development
Since the establishment of Seattle as an exchange in 1883, telephone development has kept pace with the growth of the city now listed as the 19th largest in the U.S. Evidence of this development and the future growth trend is indicated below:
| Period | Telephones In Service (End of Period) |
|---|---|
| 1883-1903 | 10,000 |
| 1903-1923 | 80,000 |
| 1923-1943 | 175,000 |
| 1953-1963 | 430,000 |
| 1-1-66 Actual | 445,000 |
| 1-1-75 Est. | 750,000 |
Past Developments
Initial dial service was provided by panel type switching equipment in 1923 with additional dial units installed in 1924 and 1927.
The first two No. 1 crossbar switching machines were installed in 1941 as growth units in existing panel offices. Subsequent installations of No. 1 crossbar in 1942, 1945, and 1949 were used to complete the conversion program to dial service.
By 1948 sufficient No. 1 crossbar equipment was in plant to take advantage of crossbar tandem to achieve interlocal trunking economies. Accordingly Mutual tandem was established that year. In view of mechanized toll operation at many points interconnecting with Seattle a need for incoming toll dialing developed immediately thereafter and Mutual tandem has been used as a combined toll and local machine ever since.
Seattle became 100% dial in 1949 with the elimination of the last manual board at Glendale in the Cherry district.
In 1954 the establishment of extended area service (EAS) in the "Greater Seattle Area" made it necessary to establish a second crossbar unit (East XBT).
All of the panel units in Seattle were originally equipped with translator type senders which are limited to six digits and 40 central office codes. Modification of these switches was made in 1954 which provided a limited number of additional codes to meet EAS requirements.
1956
Seattle – Issaquah EAS was established.
The first No. 5 crossbar machines were installed in 1957 as growth units.
A total of 12 #5XB marker groups are in service in the Seattle exchange at this time (1-1-67) for P.O.T.S. – Centrex and CCSA services. Additional #5XB units are programmed for growth and panel replacement thru 1969.
To obtain additional codes to meet growth requirements and to provide for 2-5 numbering all translator senders were replaced with decoder senders except in the panel units downtown. Since about one half of the total number of translator senders in Seattle were located downtown it was found more economical on long term basis to replace these units with No. 5 crossbar.
1958
2L - 5N Dialing was established in the Seattle calling area.
Emerson XBT Tandem was established in 1958 to care for the growth and dialing problems with the EAS service between Seattle and the West Coast Telephone Company exchanges to the north.
1959
Seattle was established as a sectional center in the national DDD network with the installation of a 4A toll switching machine in the 1200 3rd Avenue (Mutual) building. Initially all of Washington, part of Idaho and Alaska was served from the Seattle machine. However, with the establishment of Spokane as a sectional center in 1960 the Seattle 4A now serves class 4 toll centers in western Washington and Alaska only.
Mutual XBT was designated a class 4 switch point with the installation of the Seattle 4A machine.
1960
Seattle – Kent EAS was established.
1961
DDD was established for all Seattle offices.
1965
Seattle – Maple Valley
EAS was established.Future Developments
The continued demands for more and better telephone service in the Seattle area will require several major programs during the future years. Among these are:
Touch-Tone Calling
Provision of Touch-Tone Calling capabilities in all Seattle districts during the period 1968-1971.
Touch-Tone Calling features are not planned for the panel C.O. units.
Dial To Dial Replacements
It is presently planned to have all panel units replaced with either #5XB or #1 ESS units by the end of 1974.
The phasing out of the #1XB units is not expected to start for at least 10 more years.
#5XB units will be retained indefinitely.
The large SXS 701 PBX at Boeing Plant #2 is planned for replacement during the 1969-1970 period. Other larger SXS PBX units in Seattle are expected to converted [sic] to #5XB or #1 ESS C.O. CENTREX or #101 ESS C.U. CENTREX within the next 10 years.
Central Office Districts
No new districts (wire centers) are planned within the Seattle exchange during the next 10 years. However, new unit starts are planned in at least 10 of the 12 existing central offices. This includes the panel replacements mentioned above.
District boundaries will generally remain as they now exist. With the possible exception of a Melrose – Sunset area transfer only minor adjustments in boundaries are anticipated at this time.
Traffic Service
Seattle is programmed for the W-I Area's first T.S.P.S. installation starting in 1970. It is expected that all 3CL switchboards in Seattle will have been replaced and full T.S.P.S. operation established by 1975.
A new "downtown" toll operations building for T.S.P.S. installation and auxiliary positions is planned for occupancy in 1970. Ultimately no traffic operations will remain in the 1120 nor the 1200 Avenue buildings. Likewise the traffic operations will be removed from the existing Lakeview (North Toll) building. All such space released will be utilized for equipment.
New toll operating space for T.S.P.S. will be required in both north and south Seattle during the period 1973-1975.
Extended Area Service
Expansion of the calling scope of the Seattle exchange will continue to expand. A comprehensive EAS arrangement for the Everett – Seattle – Auburn – Tacoma area is under study at this time. It is expected that beginning with the establishment of the Seattle Metro Plan in 1970, such a plan will be realized within the next 10 to 15 years.
The implementation of these programs along with other past and future development for each Seattle office district is presented in the following pages.