In India, phone numbers have a fixed 10-digit length. This length includes the subscriber number and the area code. Each city and town in India is assigned one of these codes, which vary in length from two to eight digits. Therefore, a subscriber number cannot be longer than eight digits.
Each area code for India is assigned according to the National Numbering Plan that the authorities prepared in 2003. This plan was later revised in 2015. The largest cities and metropolitan areas in the country have 2-digit codes. Three-digit codes are assigned to cities of smaller size but still some significance.
To make the assignment of area codes easier, India is divided into 8 large zones. Hence, each code within this zone begins with a digit that goes from 1 to 8. Let us see some examples of how this works for large metropolitan areas and mid-sized cities:
For zone 1 we have New Delhi (11) and Jaipur (141);
For zone 2 we have Mumbai (22) and Nashik (253);
For zone 3 we have Kolkata (33) and Durgapur (343);
For zone 4 we have Chennai (44) and Madurai (452);
For zone 5 we have Kanpur (512);
For zone 6 we have Patna (612);
For zone 7 we have Ahmedabad (79) and Nagpur (712);
For zone 8 we have Bengaluru (80) and Belgaum (831).
As seen, there are no big metropolitan areas within zones 5 and 6. On the other hand, there are two other big cities with 2-digit area codes. These are Pune with code 20 and Hyderabad with code 40.
How to Dial Local Numbers in This Country
Within the country, you do not have to dial any prefix if you call a number in the same zone. No code is needed either. For instance, to dial a number in Nagpur, you just dial directly the subscriber number xxx xxxx. In this case, the subscriber number is 7-digit long.
Now, if you dial the same number from the capital city, you have to add the prefix ‘0.’ Additionally, you have to use the corresponding code. Thus, you dial 0 (712) xxx xxxx. If you do so from a mobile phone, the same digits are used.
Now, to call a phone number in the metropolitan area of New Delhi from southern India, for example, the dialing format would be 0 (11) xxxx xxxx. Notice that the subscriber phone number is 8-digit long in this case, to comply with the national 10-digit length.
If you are in another country and want to dial into India, you have to use the +91 code. Additionally, you have to drop the ‘0’ prefix. Thus, to dial a New Delhi phone number from abroad, the format is +92 (11) xxxx xxxx.
There are some exceptions to the rules established in the numbering plan. For nearby cities or towns, separated by less than 200 km, the ‘0’ prefix can be replaced with ’95.’