Abbreviation for Wide-Area Data Service, the successor to AT&T's TWX service. Whereas TWX operated at 60 words per minute, WADS operated at 100 words per minute. In mid-1962, new area codes were allocated (510, 710, 810, and 910) for TWX and WADS services as part of a plan to integrate them with the regular direct-dialing telephone network. In the early 1970s, TWX/WADS was sold to Western Union, which eventually migrated TWX/WADS to its own network. In 1982, the TWX/WADS area codes were deallocated and reserved for later use.
Reference:
Cuccia, Mark J. "HISTORY/twx.1961.automation.plans." 16 Jan. 1997.
Townson, Patrick A. "TWX 1961 Automation Plans." 23 Jan. 1997. TELECOM Digest & Archives. http://hyperarchive.lcs.mit.edu/telecom-archives/archives/history/twx.1961.automation (4 Jun. 2001).