What is an ISD Code?

Complete guide to International Subscriber Dialling codes — how to call any country from India

What is an ISD Code?

ISD stands for International Subscriber Dialling. An ISD code is a numeric prefix assigned to each country by the International Telecommunication Union (ITU) that must be dialled before a local phone number when making an international call. It is also referred to as a country code, country calling code, or IDD code (International Direct Dialling).

India's ISD code is +91. To call an Indian number from outside India, a caller dials +91 followed by the 10-digit Indian mobile or landline number.

Important: The + symbol is shorthand for your country's international access code. In most countries (including India), + equals 00. So +91 and 0091 are the same thing. From the USA/Canada, use 011 instead of 00.

How to Make an International Call from India

Format: 00 (or +) [ISD Code] [Area Code] [Local Number]

  1. Dial + (long-press 0 on mobile) or 00 from a landline — both work identically
  2. Enter the ISD code of the destination country
  3. Omit the leading 0 from the local area code (if any)
  4. Dial the local phone number

Example: Calling Mumbai (+91, STD 022) number 28001234 from the UK: dial +91 22 28001234 or 0091 22 28001234

How to Call Popular Countries from India

USA / Canada (ISD +1)
Dial +1 [Area Code] [Number] or 001 [Area Code] [Number] — e.g. +1 212 555 1234 (New York)
United Kingdom (ISD +44)
Dial +44 [Number without leading 0] or 0044 [Number] — e.g. +44 20 7946 0958 (London)
UAE (ISD +971)
Dial +971 [Number] or 00971 [Number] — e.g. +971 4 123 4567 (Dubai)
Saudi Arabia (ISD +966)
Dial +966 [Number without leading 0] — e.g. +966 11 234 5678 (Riyadh)
Australia (ISD +61)
Dial +61 [Number without leading 0] — e.g. +61 2 9876 5432 (Sydney)
Singapore (ISD +65)
Dial +65 [8-digit Number] — e.g. +65 6123 4567

Common ISD Codes

CountryISD CodeDial from India
India+91—
United States+1001 or +1
United Kingdom+440044 or +44
Australia+610061 or +61
Canada+1001 or +1
Germany+490049 or +49
UAE+97100971 or +971
Saudi Arabia+96600966 or +966
Singapore+650065 or +65
Japan+810081 or +81
China+860086 or +86
France+330033 or +33
Bangladesh+88000880 or +880
Nepal+97700977 or +977
Sri Lanka+940094 or +94
Pakistan+920092 or +92
Malaysia+600060 or +60
South Korea+820082 or +82

View complete list of 200+ country dialling codes →

Understanding + and 00 — International Access Codes

The + symbol in phone numbers is not a decorative prefix — it represents your country's international access code (also called IDD prefix). Here's how it works:

  • From India: + = 00 — so +1 = 001, +44 = 0044
  • From USA/Canada: + = 011 — so +91 = 011-91
  • From mobile phones: Long-press 0 to get the + symbol — works universally regardless of which country you're in

Using the + format is recommended because it works from any country automatically, while 00 varies by location.

ISD vs STD Codes — What's the Difference?

  • ISD codes — used for international calls between different countries (e.g. +91 for India, +1 for USA)
  • STD codes (Subscriber Trunk Dialling) — used for long-distance calls within India between cities (e.g. 011 for Delhi, 022 for Mumbai, 040 for Hyderabad)
  • STD codes are essentially India's domestic area codes. When dialling from a mobile phone within India, STD codes are part of the 10-digit number and no prefix is needed.

Learn more about STD codes →

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Frequently Asked Questions

What is an ISD code?▼
ISD stands for International Subscriber Dialling. An ISD code (also called a country calling code or country code) is a numeric prefix dialled before a telephone number to connect an international call to the correct country.
What is India's ISD code?▼
India's ISD code is +91. To call an Indian mobile or landline from abroad, dial your international access code (usually +) followed by 91, then the 10-digit Indian phone number (without the leading 0).
How do I call USA from India?▼
From India, dial +1 (or 001) followed by the 10-digit US phone number (area code + local number). Example: +1 212 555 1234 to call New York.
How do I call UK from India?▼
From India, dial +44 (or 0044) followed by the UK number without the leading 0. Example: +44 20 7946 0958 to call London.
How do I dial an international number from India?▼
From India, dial 00 (international access code) or + on mobile phones, then the country's ISD code, then the local phone number (omit the leading 0 if the local number has one). Example: To call the UK (+44): dial +44 20 7946 0958.
What is the difference between ISD and STD codes?▼
ISD (International Subscriber Dialling) codes are used for international calls between countries. STD (Subscriber Trunk Dialling) codes are used for long-distance calls within India between cities (e.g. 011 for Delhi, 022 for Mumbai).
Are ISD codes and country codes the same thing?▼
Yes — ISD codes, country codes, country calling codes, and IDD (International Direct Dialling) codes all refer to the same thing: the numeric prefix that identifies a country in the international telephone numbering plan (ITU-T E.164).
Is +91 and 0091 the same?▼
Yes. +91 and 0091 both reach India. The + symbol is a universal shorthand for the international access code. From most countries, dialling 00 before 91 achieves the same result. From the US/Canada, the access code is 011, so you would dial 011-91.
How many ISD codes are there in the world?▼
There are approximately 250 country/territory codes assigned by the ITU (International Telecommunication Union). Some regions share codes (e.g. +1 covers USA, Canada, and Caribbean nations), and some territories have their own separate codes.