+853

Macau maintains its own telephone numbering plan during both Portuguese and Chinese administration. Calls to mainland China, Hong Kong, Taiwan and Portugal are international.

Country Code: +853
International Call Prefix: 00
Trunk Prefix: none
Area Code: not used

Prior to 1999 telephone regulation was under the Direcção dos Serviços de Correios e Telecomunicações (CTT) or Posts, Telegraphs and Telephones under the Secretary for Transport and Public Works.

Since 1999 telephone numbers are under the responsibility of the Direcção dos Serviços de Regulação de Telecomunicações (DSRT) or Bureau of Telecommunications Regulation under the Secretariat for Transport and Public Works.

The alternative shortcut way to dial Hong Kong numbers is shown as follows:

Same as Hong Kong, the telephone number for emergency services – Police, Fire Service and Ambulance – is 999.

Some special numbers are 3-digit or 4-digit.

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Wikipedia