Mobile telephone numbering in India
In India, mobile numbers on GSM, WCDMA, LTE and NR networks start with either 9, 8, 7 or 6. Each telecom circle is allowed to have multiple private operators; previously it was two private + BSNL/MTNL, subsequently it changed to three private + BSNL/MTNL in GSM; however currently each telecom circle has all four operators including Reliance Jio, Bharti Airtel, Vodafone Idea and BSNL/MTNL.
All mobile phone numbers are 10 digits long. The way to split the numbers is
defined in the National Numbering Plan as XXXXX-NNNNN. Here, XXXXX identifies the network operator and the telecom circle while NNNNN identifies the subscriber.
While 'XXXXX' used to be network operator identification. Due to Mobile number portability XXXXX-NNNNN no longer a good way to split. Instead XXXX-NNN-NNN is a better format. Where XXXX represents the geographic location and NNN-NNN represents the subscriber number. This split of XXXX-NNN-NNN offers better readability.
Telecom circles
The Department of Telecommunications has divided India into various telecom circles such that within each circle, the call is treated as a local call, while across zones, it becomes a long-distance call. As of July 2018 there are 22 telecom circles or service areas. They are classified into four categories: Metro, A, B, C. Chennai, Delhi, Mumbai, and Kolkata fall under Metro category.A telecom circle is normally the entire state, with a few exceptions like Mumbai and Kolkata, Goa, Chhattisgarh, Sikkim Jharkhand, Northeastern states except Assam and Sikkim or Uttar Pradesh. Delhi is a unique circle because it includes cities from Haryana and Uttar Pradesh as well. The new state of Telangana remains in the same circle as Andhra Pradesh.
From May 20, 2005, calls between Mumbai Metro and Maharashtra Telecom Circle, between Chennai Metro and Tamil Nadu Telecom Circle, and between Uttar Pradesh and Uttar Pradesh Telecom Circle service areas are merged in Inter service area connected in the above-mentioned four states would be treated as intra-service area call for the purposes of routing as well as Access Deficit Charges. The dialing procedure for calls within a state for these states would also be simplified, i.e. dialing of mobile-to mobile subscribers and fixed-to-mobile subscribers would be without prefixing '0'.
In December 2017, Reliance Jio started with the newest of all, "the six-series-mobile numbers", keeping in mind the growing number of users in India. The growth in the number of 4G users in the country has made the 4G base larger than the 2G users in India pushing number of 2G users to second position.
| Circle name | Code | Category | Geographic area covered |
| Andhra Pradesh | AP | A | State of Andhra Pradesh, State of Telangana and Yanam district |
| Assam | AS | C | State of Assam |
| Bihar & Jharkhand | BR | C | State of Bihar and State of Jharkhand |
| Chennai | CH | Metro | Chennai, upto Maraimalai Nagar, Minjur and Mahabalipuram |
| Delhi | DL | Metro | Union Territory of Delhi, Faridabad district and Gurgaon district in Haryana, Ghaziabad district and Gautam Buddh Nagar district in Uttar Pradesh |
| Gujarat | GJ | A | State of Gujarat and Union Territory of Dadra and Nagar Haveli and Daman and Diu |
| Himachal Pradesh | HP | C | State of Himachal Pradesh |
| Haryana | HR | B | State of Haryana. |
| Jammu and Kashmir | JK | C | Union Territory of Jammu and Kashmir and Union Territory of Ladakh |
| Kerala & Lakshadweep | KL | B | State of Kerala, Union Territory of Lakshadweep and Mahé district |
| Karnataka | KA | A | State of Karnataka |
| Kolkata | KO | Metro | Kolkata |
| Maharashtra & Goa | MH | A | State of Maharashtra and State of Goa |
| Madhya Pradesh & Chhattisgarh | MP | B | State of Madhya Pradesh and State of Chhattisgarh |
| Mumbai | MU | Metro | Mumbai, Navi Mumbai, Thane and Kalyan |
| North East | NE | C | State of Arunachal Pradesh, State of Manipur State of Meghalaya, State of Mizoram, State of Nagaland and State of Tripura |
| Odisha | OR | C | State of Odisha |
| Punjab | PB | B | State of Punjab, Union Territory of Chandigarh and Panchkula district |
| Rajasthan | RJ | B | State of Rajasthan |
| Tamil Nadu | TN | A | State of Tamil Nadu, Puducherry district and Karaikal district |
| UP | UE | B | Eastern Uttar Pradesh |
| UP | UW | B | Western Uttar Pradesh and State of Uttarakhand |
| West Bengal | WB | C | State of West Bengal, State of Sikkim and Union Territory of Andaman and Nicobar Islands |
Network operators
| AT | Airtel India |
| CG | BSNL/MTNL - Central Gov. |
| RJ | Reliance Jio |
| VI | Vodafone Idea |
- Note: The mobile numbers and operators are subject to change since Mobile number portability is available in most circles.
- Note: Chennai circle was merged with Tamil Nadu circle in 2005.