400 telephones are divided into 4006 (China Unicom), 4007 (China Mobile's former Tietong), 4008 (China Telecom), 400 1 (China Mobile's new section), 4000 (China Unicom's new section) and 4009 (China Telecom's new section).

400 telephone calls are limited to enterprises or industrial and commercial households with industrial and commercial licenses, and individuals are absolutely not allowed to handle them. This is the basis of the two premises and the first condition, and it is not allowed for licensed enterprises or individual industrial and commercial households to handle it uniformly, which is also an absolute guarantee for the regularity of 400 telephones.

Extended data

Telephone advantages:

First, the most important point of 400 telephone is to establish a good image for the enterprise;

Second, the enterprise 400 phone will not be busy, which avoids the problem that the business phone is busy before;

Third, the calling/called party shares the payment, effectively eliminating malicious calls (800 number callers are free);

Fourth, self-management, convenient and fast, low cost, the number is carried for life, and the number is not changed.