Working out Indian STD Codes

On this page we will outline some rules of thumb for making sense of the vast network of STD local access codes that help direct the Indian landline telephone network. We will examine how to work out what the STD code is in a landline telephone number. Also we will look at why some STD codes are longer than others. In doing this we will see what we can learn about the area covered by an STD Code just by looking at the STD code itself. So look at the rules which we provide below and give any suggestions and corrections you may have in the comments section below.

Rule 1: the larger the STD code the smaller the area it covers

The best evidence for this assertion is that there are only 8 places covered by three digit STD codes and these are all tier 1 cities. All other cities, villages and other areas have STD codes of at least 4 digits. So is there a strong inverse correlation between size of the city and size of the STD code?

Let's examine this by looking first at the tier 1 cities and their STD codes, they are:

011 - Delhi

020 - Pune

022 - Mumbai

033 - Calcutta

040 - Hyderabad

044 - Chennai

079 - Ahmedabad

080 - Bangalore

The above cities are ranked from lowest number 011 which is the STD code of the capital Delhi, to Bangalore which has the highest STD code number - 080. Given that these are the only cities with three digit STD codes, can we also assume that they are the biggest cities? Well let's use population to test the theory.

Below we order the top eight Indian cities by population, with Mumbai beginning the list as it is the most populous city in India.

1. Mumbai (pop 12.5 million) STD - 022
2. Delhi (11 million) - 011
3. Bangalore (8.5 million) - 080
4. Hyderabad (6.8 million) - 040
5. Ahmedabad (5.5 million) - 079
6. Chennai (4.7 million) - 044
7. Kolkata (4.5 million) - 033
8. Surat (4.4 million) - 0261.

We can see here that there is a direct correlation between population size and likelihood of having a three digit STD code. In fact of the 8 three digit STD codes that are in operation 7 have been awarded to cities that are among the eight most populous in the country. Only one tier 2 city appears in the list above which is the rapidly expanding city of Surat. Note that as a tier 2 city it has a four digit STD code (0261). Pune is the only tier 1 city that is not among the eight most populous Indian cities.

Rule 2  - All Indian local STD access code begin with '0'

Although understanding Indian Access codes is a complicated business one thing that holds true for all of them and that is that they all begin with zero. However, this rule does need to be broken if you are calling an Indian landline from outside the country. In fact the rule needs to be reversed: If calling an Indian landline from outside India no STD codes begin with zero.

This is because the zero that begins STD codes in India are replaced by the India national access code of +91 in calls to the country from abroad.

Rule 3 - Tier 2 Cities All have four digit STD codes

Yes all tier 2 cities in India have four digit STD codes. There are 99 tier 2 cities in India and they all have four digit STD codes.

STD Codes

Welcome to our site. On these pages we aim to demystify the nearly 2500 Codes that are used in the Indian landline telephone system.

Starting with the 011 STD code for Delhi we will move through to the smaller areas around iandia which have much longer STD codes.  For example we will look at Addagal in Karnataka state which has an 8 digit STD code: 08157476. We to make the process of understanding and using these codes simpler than ever before.

We will also provide adequate search facilities so that you can search for the specific STD  code of the geographical area you need to call. We are here to do the research so that you don't have to. For each STD code, whether it is for a city, town or village we provide examples where the local access STD code is in use. This way our readers are able to identify exactly where the STD codes appear in a call to a local number.