Postal, telegraph and telephone service

A postal, telegraph, and telephone service (or PTT) is a government agency responsible for postal mail, telegraph, and telephone services. Such monopolies existed in many countries, though not in North America or Japan. Many PTTs have been partially or completely privatised in recent years. In some of those privatisations, the PTT was renamed completely (such as the present-day KPN in the Netherlands, Orange S.A. in France, BT Group in the United Kingdom, Telkom SA in South Africa and A1 Telekom Austria Group in Austria), whereas in others, the name of the privatised corporation has been only slightly modified, such as PT Telkom in Indonesia and Post and Telecom of Kosovo in Kosovo.
Monopoly service.
In countries that had a PTT unit of government, typically the vast majority of forms of distribution of information fell under the auspices of the PTT, whether that be the delivery of printed publications and individual letters in the postal mail, the transmission of telephonic audio, or the transmission of telegraphic on-off signals, and in some countries, the broadcast of one-way (audio) radio and (audio-video) television signals. In many countries with a current or former PTT, the PTT was also responsible for the manufacture and standardisation of telephone equipment. Often the presence of a single PTT in a country implied a single monolithic approach to the distribution of information in that country, which as an advantage permitted efficient deployment of a single national standard for each topic instead of ongoing debate about competing ideas, but which as a disadvantage typically stifled alternative ideas from emerging once a legacy implementation had been widely deployed.
Mixed service.
In North America, instead of a PTT there was the private monopoly Bell System (for the US)/Bell Canada (dominant ILEC in Ontario, Quebec and (historically) parts of what is now Nunavut; competes with other fixed-line carriers in the rest of Canada) responsible for telecommunications and a separate federally run US Postal Service/Canada Post for mail delivery. Japan also had a rather similar structure as North America with the formerly-state-owned Nippon Telegraph and Telephone (NTT; privatised in 1985) having a monopoly on fixed-line telecoms, with the separate government-run but publicly-traded Japan Post responsible for mail delivery.
Portugal, until 1968, had a mixture, with a private telecom operator in Lisbon and Porto (named APT – Anglo-Portuguese Telephone Company) another private company in charge of connections with and between colonies and with the rest of the world (CPRM – "Companhia Portuguesa de Rádio Marconi") and "Correios, Telefones e Telégrafos", a public company, as the owner of the telephone system in the rest of the country (including the former colonies); that year, APT was nationalised and became "Telefones de Lisboa e Porto" (TLP). CTT still controls postal services in Portugal, while Telecom Portugal was spun out in 1992 and later merged into Portugal Telecom in 1994 (with CPRM becoming a subsidiary and later being absorbed in 2002); it is privatised and subject to competition.