Telephone numbers in Asia

E.164 is an international standard, titled The international public telecommunication numbering plan, that defines a numbering plan for the worldwide public switched telephone network (PSTN) and some other data networks.

A toll-free telephone number or freephone number is a telephone number that is billed for all arriving calls. For the calling party, a call to a toll-free number from a landline is free of charge. A toll-free number is identified by a dialing prefix similar to an area code. The specific service access varies by country.

Subscriber trunk dialling (STD), also known as subscriber toll dialing, is a telephone numbering plan feature and telecommunications technology for the dialling of trunk calls by telephone subscribers without the assistance of switchboard operators.

A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, reachable by a system of destination code routing. Telephone numbering plans are defined in each of the administrative regions of the public switched telephone network (PSTN) and in private telephone networks.

E.123 is an international standard by the standardization union (ITU-T), entitled Notation for national and international telephone numbers, e-mail addresses and Web addresses. It provides guidelines for the presentation of telephone numbers, email addresses, and web addresses in print, on letterheads, and similar purposes.

International direct dialing (IDD) or international subscriber dialling (ISD) is placing an international telephone call that is dialed directly by a telephone subscriber, rather than by a telephone operator.

In Argentina, area codes are two, three, or four digits long. Local customer numbers are six to eight figures long. The total number of digits is ten, for example, phone number (11) 1234-5678 for Buenos Aires is made up of a 2-digit area code number and an 8-digit subscriber's number, while (383) 123-4567 would be an example of a Catamarca number.

A trunk prefix is a digit sequence to be dialed before a telephone number to initiate a telephone call for the purpose of selecting an appropriate telecommunications circuit by which the call is to be routed.

A telephone prefix is the first set of digits after the country, and area codes of a telephone number; in the North American Numbering Plan countries, it is the first three digits of a seven-digit phone number, 3-3-4 scheme. In other countries both the prefix and the number may have different lengths. It shows which exchange the remaining numbers refer to. A full telephone number is usually made up of a country code, area code, prefix, and subscriber number.