Why 8xx number is assigned for call center?
Traditionally, the area code 800 was used for the
'transferred-charge service' in the United Kindgdom, put in place
by the Post Office in 1934. At this time, 8xx numbers were
classified as collect calls.
Later, in 1978, Roy P. Weber created the second generation
toll-free phone system, and used the 8xx area codes, patenting the
technology as the 'Data Base Communication Call Processing Method',
which later became known as the 'Toll-Free Call' or '1-800
Numbers'.
The following 8xx area codes are also reserved for similar
informational services:
888 (since 1996)
877 (since 1998)
866 (since 2000)
The area codes 855 , 844, 833, 822, 880 through 887, and 889 are
also reserved, but are not yet in use.