Indian Phone Number System
Prashanth Kancherla
Jun 18, 2026 | 10 mins read
Calling someone in India sounds simple until you’re staring at a number and second-guessing whether it needs a zero in front, a +91, or nothing at all. This guide cuts through that confusion. Whether you’re dialing domestically or internationally, from a mobile or a landline, every format and rule you need is right here.
Key Takeaways
If you read nothing else, remember these eight things:
- Indian mobile numbers are always 10 digits. No exceptions. Don’t add a zero. Don’t add +91 unless calling from outside India.
- The prefix tells you where the number was born — not where it lives. MNP means the operator can change at any time. India has processed over 1 billion MNP requests since 2011. Use TRAI’s 1900 SMS lookup to verify.
- The 0 prefix is for inter-city landline calls and landline-to-mobile calls. Since 15 January 2021 (DoT mandate), all landline-to-mobile calls must be dialled with a 0 prefix. Never use 0 before a mobile number when calling mobile-to-mobile.
- +91 is for calling India from abroad only. Don’t use it for domestic calls within India.
- Always use the + format in your phone contacts. It’s universal, works across VoIP apps, survives roaming, and eliminates the 00-vs-011 confusion entirely.
- Landlines are niche but alive — and actually growing. India’s wireline base reached ~48.58 million in April 2026, up from 33.79 million in March 2024, driven by fiber rollouts.
- Toll-free numbers (1800 series) don’t work from outside India. If building an international outbound campaign, don’t dial these — use local equivalents instead.
- MNP was introduced in 2011; nationwide portability launched in July 2015. The original 2011 rollout was intra-circle only. July 2015 enabled porting across states and circles.
In this article, we will explore:
- 1. Indian Mobile Number Structure
- 2. Operator Prefix Ranges
- 3. Mobile Number Portability (MNP)
- 4. Special Number Series
- 5. STD Codes — Metros and Major Cities
- 6. How to Dial a Landline from Mobile
- 7. Dialing Rules: Mobile to Mobile and Landline
- 8. The Trunk Prefix 0 — When to Use, When to Drop
- 9. Common Mistakes and Fixes
- 10. International Dialing to and from India
- 11. Calling India from Abroad — Format Table
- 12. Calling Abroad from India — Format Table
- 13. Country Code Quick-Reference
- 14.+ vs 00 — Roaming and VoIP Rules
Indian Mobile Number Structure
The Indian mobile numbering system is designed to uniquely identify subscribers, facilitate seamless routing of calls and messages, and accommodate the rapidly growing demand for mobile services.The 10-Digit Format
Every Indian mobile number is exactly 10 digits — no exceptions, no leading zeros, no country code added for domestic calls. The moment you add a zero in front of a mobile number while calling from another mobile within India, you have broken it. That 10-digit constraint is the single most important rule to internalize, because it underpins every dialing decision you will make. The first four digits historically identified the operator and telecom circle, but with mobile number portability now in full swing, the prefix is no longer a reliable proxy for who your recipient’s carrier is| Dimension | Virtual Number | Traditional Landline | SIM-Based Mobile |
|---|---|---|---|
| Setup time | Minutes to hours (online) | Days to weeks (physical installation) | Hours (SIM activation) |
| Monthly cost | ₹150–₹800 local; ₹1,000–₹3,000 toll-free | ₹500–₹2,000 + hardware | Variable per-SIM cost |
| Scalability | Instant via dashboard | New physical lines required | Limited by SIM inventory |
| Call recording | Built-in, server-side | Requires additional hardware | Device-dependent |
| CRM integration | Native APIs, screen-pop, auto-logging | Middleware or manual entry required | App-based workarounds only |
| Remote access | Any device, any location | Fixed to office location | Tied to SIM and handset |
| Agent privacy | Personal numbers always masked | Not applicable | Agent number exposed |
| TRAI compliance | DLT, DND scrubbing, 160-series support built-in | Manual compliance processes required | No built-in compliance tooling |
Operator Prefix Ranges
If you’re building a dialer or validating numbers programmatically, the starting digits map to specific operators — but remember, MNP means the actual operator behind any given number may differ from its original allocation.
Table A: Operator → Prefix Series → Starting Digits
| Operator | Starting Digits | Sample Prefix Series | Notes |
|---|---|---|---|
| Jio | 6, 7 | 60x, 61x, 62x, 70x, 71x | Largest 6xxx block holder; ~476M subscribers (Dec 2024) |
| Airtel | 7, 8, 9 | 72x, 73x, 80x, 81x, 98x, 99x | Widest prefix range; ~289M subscribers (Dec 2024) |
| Vi (Vodafone Idea) | 7, 8, 9 | 70x, 77x, 82x, 95x, 96x | Combined Vodafone-Idea blocks; ~126M subscribers (Dec 2024) |
| BSNL | 7, 9 | 70x, 94x, 95x | Government operator; declining subscriber base |
| MTNL | 9 | 98x (Delhi & Mumbai) | Operates only in Delhi and Mumbai; shrinking subscriber base |
Table B: Starting Digit → Possible Operators (Quick-Lookup)
| First Digit | Possible Operators |
|---|---|
| 6 | Jio |
| 7 | Jio, Airtel, Vi, BSNL |
| 8 | Airtel, Vi |
| 9 | Airtel, Vi, BSNL, MTNL |
Mobile Number Portability (MNP)
MNP is the reason you cannot trust a prefix anymore. Mobile Number Portability was first introduced in India on 20 January 2011 (initially limited to within a telecom circle). On 3 July 2015, pan-India nationwide portability launched — allowing subscribers to switch operators while retaining their number across circles and states.
As of July 2024, India had processed over 1 billion MNP requests since the service launched. Approximately 11 million porting requests are processed each month.
| Method | How to Use | Response Time |
|---|---|---|
| TRAI SMS (PORT) | SMS PORT <10-digit number> to 1900 | Instant reply with UPC code |
| Truecaller / Carrier Apps | Search the mobile number within the app | Immediate (crowdsourced) |
| Operator Customer Care | Call 198 or the operator’s customer support helpline | 2–5 minutes |
| TRAI Website | Use MNP lookup tools available on trai.gov.in | Real-time |
Special Number Series
Not all Indian numbers are created equal. Some cost the caller nothing; others are designed to cost the business calling you; a few are reserved for emergency access.
| Series | Type | Chargeable to Caller? | Example |
|---|---|---|---|
| 1800-xxx-xxxx | Toll-Free | No (caller pays nothing) | 1800-180-1234 |
| 140xx | Telemarketing / Promotional | No to recipient; sender bears operator cost | 14012, 14055 |
| 1600-xxx-xxxx | Incoming-Only Customer Service | Local call rate applies | 1600-103-4567 |
| 112 | National Emergency Number | No | 112 |
| 1xx | Government Helplines | Free or local rate | 100 (Police), 101 (Fire), 104 (Health), 108 (Ambulance) |
Landline Quick Reference
Landlines in India are in structural transition — not decline. India’s wireless subscriber base stood at approximately 1.17 billion as of June 2025 (TRAI). Meanwhile, wireline connections have actually been growing: wireline subscribers reached 48.58 million by April 2026 (up ~9.6% year-on-year from March 2024 to March 2025), driven by Jio and Airtel fiber expansion.
Government offices, hospitals, municipal bodies, and legacy businesses still depend on landlines, and the dialing rules differ enough from mobile that getting them wrong means a dead line.
STD Codes — Metros and Major Cities
| City | STD Code | How to Dial | Subscriber Digits |
|---|---|---|---|
| Delhi | 11 | 0-11-XXXXXXXX | 8 |
| Mumbai | 22 | 0-22-XXXXXXXX | 8 |
| Kolkata | 33 | 0-33-XXXXXXXX | 8 |
| Chennai | 44 | 0-44-XXXXXXXX | 8 |
| Bengaluru | 80 | 0-80-XXXXXXXX | 8 |
| Hyderabad | 40 | 0-40-XXXXXXXX | 8 |
| Pune | 20 | 0-20-XXXXXXXX | 8 |
| Ahmedabad | 79 | 0-79-XXXXXXXX | 8 |
| Jaipur | 141 | 0-141-XXXXXXX | 7 |
| Lucknow | 522 | 0-522-XXXXXXX | 7 |
| Chandigarh | 172 | 0-172-XXXXXXX | 7 |
| Surat | 261 | 0-261-XXXXXXX | 7 |
| Kochi | 484 | 0-484-XXXXXXX | 7 |
| Nagpur | 712 | 0-712-XXXXXXX | 7 |
| Bhopal | 755 | 0-755-XXXXXXX | 7 |
| Patna | 612 | 0-612-XXXXXXX | 7 |
| Indore | 731 | 0-731-XXXXXXX | 7 |
| Coimbatore | 422 | 0-422-XXXXXXX | 7 |
How to Dial a Landline from Mobile
From 15 January 2021, the Department of Telecommunications (DoT) mandated that all landline-to-mobile calls must be prefixed with 0. Mobile-to-mobile and mobile-to-landline dialing rules remain unchanged. If calling a mobile from a landline, dial 0 + 10-digit mobile number.
| Scenario | Format to Dial | Example |
|---|---|---|
| Same City (Local) | Full 10-digit format recommended | 011-2345-6789 |
| Different City (Domestic) | 0 + STD Code + Subscriber Number | 0-80-2345-6789 (Bengaluru) |
| From Abroad | +91 + STD Code (without leading 0) + Subscriber Number | +91-11-2345-6789 (Delhi) |
Dialing Rules: Mobile to Mobile and Landline
Mobile-to-mobile calls within India need only the 10-digit number — no prefix, no STD code, no country code.
Format by Call Scenario
Every call scenario has its own format rule. The golden rule: mobile-to-mobile calls within India need nothing but the 10-digit number.
| Call Type | Format | Example | Note |
|---|---|---|---|
| Mobile → Mobile (Same Operator) | 10-digit number directly | 98765 43210 | No prefix required |
| Mobile → Mobile (Any Operator) | 10-digit number directly | 70123 45678 | MNP means prefix no longer identifies operator |
| Mobile → Landline (Same City) | Full 10-digit format recommended | 011-2345-6789 | Best practice since Jan 2021 |
| Mobile → Landline (Different City) | 0 + STD code + subscriber number | 0-22-2345-6789 | Leading 0 is mandatory |
| Landline → Mobile (Any Network) | 0 + 10-digit mobile number | 0-98765-43210 | Mandatory from 15 Jan 2021 (DoT) |
| Toll-Free from Mobile | Dial as-is | 1800-103-4567 | No prefix required; free to call |
The Trunk Prefix 0 — When to Use, When to Drop
| Call Type | Use 0? | Use +91? | Example |
|---|---|---|---|
| Mobile → Mobile (Domestic) | No | No | 98765 43210 |
| Mobile → Landline (Same City) | No | No | 2345 6789 or full 10-digit format |
| Mobile → Landline (Different City) | Yes | No | 0-11-2345-6789 |
| Landline → Mobile | Yes | No | 0-98765-43210 |
| Calling India from Abroad | No (drop the 0) | Yes | +91-98765-43210 |
| Calling Abroad from India | No | Use + or 00 | +44-20-1234-5678 |
Common Mistakes and Fixes
| Mistake | What Happens | Correct Format |
|---|---|---|
| Dialing 0 before mobile number (mobile → mobile) | Call may fail or route incorrectly | Dial the 10-digit mobile number directly |
| Omitting 0 before STD code for inter-city landline | Call does not connect | 0 + STD Code + Subscriber Number |
| Using +91 for domestic landline calls | Call may not connect correctly | Use 0 + STD Code + Subscriber Number |
| Landline calling mobile without 0 prefix | Blocked or fails since Jan 2021 | Dial 0 + 10-digit mobile number |
| Keeping leading 0 in STD code when dialing from abroad | Number routes incorrectly | Drop the 0: +91-11-XXXXXXXX |
| Dialing international numbers without ISD activation | Call blocked by operator | Activate ISD through operator app or customer care |
International Dialing to and from India
India’s country code is +91, assigned by the ITU under E.164. Use + format universally — it works across VoIP, roaming, and all devices.
India’s Dialing Codes at a Glance
| Code Type | Value | When Used | Example |
|---|---|---|---|
| Country Code | +91 | Used when calling India from another country | +91-98765-43210 |
| IDD Exit Prefix (India) | 00 | Dial before the destination country code when calling abroad from India | 00-44-20-1234-5678 |
| Alternative Exit Prefix | + | Universal international dialing prefix supported by modern devices | +44-20-1234-5678 |
| Trunk Prefix (Domestic) | 0 | Used before STD code for inter-city landline calls within India | 0-11-2345-6789 |
Calling India from Abroad — Format Table
| Destination Type | Full Dial Format | Worked Example |
|---|---|---|
| Indian Mobile | +91 + 10-digit mobile number | +91-98765-43210 |
| Landline (Metro, 2-digit STD) | +91 + STD code (without leading 0) + 8-digit subscriber number | +91-11-2345-6789 (Delhi) |
| Landline (Tier-2 / Tier-3 City, 3-digit STD) | +91 + STD code (without leading 0) + 7-digit subscriber number | +91-141-234-5678 (Jaipur) |
| Toll-Free (1800 Series) | Usually not accessible directly from abroad; use local or international support number | — |
Calling India from Abroad — Format Table
| Destination Type | Full Dial Format | Worked Example |
|---|---|---|
| Indian Mobile | +91 + 10-digit mobile number | +91-98765-43210 |
| Landline (Metro, 2-digit STD) | +91 + STD code (without leading 0) + 8-digit subscriber number | +91-11-2345-6789 (Delhi) |
| Landline (Tier-2 / Tier-3 City, 3-digit STD) | +91 + STD code (without leading 0) + 7-digit subscriber number | +91-141-234-5678 (Jaipur) |
| Toll-Free (1800 Series) | Usually not accessible directly from abroad; use local or international support number | — |
Calling Abroad from India — Format Table
| Destination | Country Code | Full Dial Format from India | Notes |
|---|---|---|---|
| USA / Canada | +1 | 00-1-212-555-0100 or +1-212-555-0100 | Same country code is used for both USA and Canada |
| United Kingdom | +44 | 00-44-20-1234-5678 or +44-20-1234-5678 | Remove the leading 0 from UK numbers |
| UAE | +971 | 00-971-50-123-4567 or +971-50-123-4567 | Mobile numbers commonly start with 50, 55, or 56 |
| Australia | +61 | 00-61-2-9876-5432 or +61-2-9876-5432 | Remove the leading 0 from Australian numbers |
| Germany | +49 | 00-49-30-1234-5678 or +49-30-1234-5678 | Remove the leading 0 from German numbers |
| Singapore | +65 | 00-65-6123-4567 or +65-6123-4567 | No trunk prefix to remove |
| Nepal | +977 | 00-977-1-234-5678 or +977-1-234-5678 | Standard international dialing format |
| Bangladesh | +880 | 00-880-2-123-4567 or +880-2-123-4567 | Standard international dialing format |
Country Code Quick-Reference
| Country | Code | Sample Format from India |
|---|---|---|
| USA / Canada | +1 | +1-212-555-0100 |
| United Kingdom | +44 | +44-20-7946-0958 |
| UAE | +971 | +971-50-123-4567 |
| Australia | +61 | +61-2-9876-5432 |
| Germany | +49 | +49-30-1234-5678 |
| France | +33 | +33-1-2345-6789 |
| Singapore | +65 | +65-6123-4567 |
| Japan | +81 | +81-3-1234-5678 |
| China | +86 | +86-10-1234-5678 |
| Nepal | +977 | +977-1-234-5678 |
| Bangladesh | +880 | +880-2-123-4567 |
| Sri Lanka | +94 | +94-11-234-5678 |
| Pakistan | +92 | +92-21-123-4567 |
| Saudi Arabia | +966 | +966-11-234-5678 |
| South Africa | +27 | +27-11-234-5678 |
| Malaysia | +60 | +60-3-1234-5678 |
| New Zealand | +64 | +64-9-123-4567 |
| Italy | +39 | +39-06-1234-5678 |
| Brazil | +55 | +55-11-1234-5678 |
+ vs 00 — Roaming and VoIP Rules
| Context | Use + or 00? | WhatsApp / VoIP Safe? | Roaming Safe? |
|---|---|---|---|
| Calling Abroad from India (Home SIM) | Both work | Use + format in contacts | Yes |
| On International Roaming | + strongly preferred | Use + format | Yes — 00 may fail on some networks |
| WhatsApp / iMessage / Signal Contacts | + required | Yes | Yes |
| Landline-to-International (BSNL/Airtel) | 00 standard | N/A | N/A |
| Calling India from Abroad | + preferred | Use +91 in contacts | Yes |
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Frequently Asked Questions
Dial +91 followed by the 10-digit mobile number — with no leading zero. For a number like 9876543210, dial +91-9876543210. For a landline, dial +91 + the STD code (drop the leading 0) + the subscriber number. Example: a Delhi landline becomes +91-11-2345-6789, not +91-011-2345-6789.
+91. It was assigned by the International Telecommunication Union (ITU) under the E.164 standard. It applies to both mobile and landline numbers when dialing from outside India.
No. Never. The leading zero in Indian STD codes is a domestic trunk prefix — it only works within India. Including it when dialing from abroad (e.g. +91-0-11-…) will cause the call to route incorrectly or fail entirely.
Exactly 10. All Indian mobile numbers start with 6, 7, 8, or 9. TRAI reviewed a possible move to 11 digits in 2020 to address future numbering capacity, but categorically rejected it. Instead, TRAI recommended prefixing 0 for landline-to-mobile calls (implemented January 2021), freeing up approximately 2,544 million additional numbering resources. 10 digits remains the standard.
The first digit (6–9) identifies the broad series. Digits 1–4 together identify the original operator and telecom circle allocation. Because of MNP, this is no longer a reliable indicator of the current operator — only the original one.
Same city: use the full 10-digit format (recommended). Different city: dial 0 + the STD code + the subscriber number. Example: calling a Mumbai landline from Delhi is 0-22-2345-6789.
STD (Subscriber Trunk Dialing) codes are area codes for fixed-line telephony. Major metros have 2-digit codes (Delhi: 11, Mumbai: 22, Bengaluru: 80). Smaller cities have 3–4 digit codes. Prepend 0 to the STD code when dialing inter-city from within India, and drop the 0 when dialing from abroad.
Not reliably. Mobile Number Portability, first introduced in January 2011 and expanded nationwide in July 2015, allows subscribers to switch operators while keeping their number. The original prefix maps to the original operator only. Use TRAI’s 1900 SMS service (PORT <number>) to verify the current operator.
Indian mobile numbers start with 6, 7, 8, or 9. Broadly: 6xxx is predominantly Jio; 7xxx spans Jio, Airtel, Vi, and BSNL; 8xxx is Airtel and Vi; 9xxx spans Airtel, Vi, BSNL, and MTNL. MNP means the actual operator behind any given number may not match the original allocation.
It is used before STD codes for inter-city landline calls within India, and before mobile numbers when calling from a landline (mandatory since January 2021). It must be dropped when dialing from abroad. It has no meaning outside India’s borders.
