The Indian-Mobile-OTP Problem for NRIs: Why a Dormant SIM Quietly Locks You Out of Net Banking, UPI and the Tax Portal, and How to Fix It Before You Fly

A reader in Toronto tried to log in to his Indian net banking on a Sunday night to move Rs 6 lakh into a fixed deposit before a rate change on Monday. The password went through. The OTP did not. His Indian SIM had stopped working months earlier, he had assumed the bank would simply email him, and it did not. He missed the rate. Two weeks later the same dead number cost him an evening trying to log in to the income-tax portal to file, and a card payment for an Indian insurance renewal failed because the 3D-Secure OTP went to a SIM sitting dark in a drawer in Pune. None of these were his bank closing his account. They were one small thing he let lapse, the Indian mobile number, quietly switching off four different services at once.

The 30-second answer: Most Indian banks still send the second-factor OTP only to the mobile number registered on your account, so a dormant or reassigned Indian SIM breaks net-banking logins, fund transfers, card 3D-Secure payments, UPI and even the income-tax e-filing portal. Under TRAI rules a prepaid number lapses after roughly 90 days without a recharge on Jio, Airtel and Vi (up to 180 on BSNL), then gets reassigned to a stranger. Keep one number alive with a long-validity recharge (an annual pack is around Rs 3,359 on Jio), convert it to an eSIM so it travels with you, and where your bank allows it, register your foreign number for UPI and OTPs (about twelve countries supported as of 2026). Always set up email and app-based OTP fallbacks before you fly.

This guide assumes you already know what an NRE or NRO account is and how to open one from abroad; if not, start with the NRE, NRO and FCNR account guide. What follows is the part nobody warns you about until it costs you: exactly which services break when your Indian number dies, why the income-tax portal is its own separate trap, the real cost of keeping a number alive versus the cost of losing it, which banks now accept a foreign number and which do not, and a concrete pre-departure checklist so you never get locked out at the worst possible moment.

Why one dead SIM takes down four services at once

The reason this problem blindsides people is that the Indian mobile number is not one login credential. It is the single shared key for at least four independent systems, and they fail silently and separately, so you discover each failure only when you happen to need it.

The first is net banking. Every Indian bank gates high-value actions behind a second factor, and for the overwhelming majority that second factor is an SMS OTP to the registered mobile. You can often still log in with a password, but the moment you try to add a payee, move money, change a limit or open a deposit, the system fires an OTP at a number that is no longer receiving anything. The login succeeds; the transaction dies. That gap is exactly what catches people off guard, because partial access feels like working access.

The second is debit and credit card payments. Online card transactions in India run through 3D-Secure, and the verification OTP goes to the registered mobile. An NRI paying an Indian utility bill, a health-insurance premium, a school fee or a Flipkart order from abroad will watch the payment page spin and fail at the OTP step. There is no password fallback here at all; the card is functionally unusable online without the number.

The third is UPI. UPI registration is anchored to a SIM: the app sends an outbound verification SMS from your phone to confirm the number matches the one on your bank account. Traditionally this required a live Indian SIM in the handset doing the sending, which is precisely why UPI was almost unusable for NRIs until NPCI opened it to international numbers. More on that below, because it is the one area where the rules genuinely improved.

The fourth, and the one people forget entirely, is the income-tax e-filing portal and other government services. The portal, the PAN system, DigiLocker and Aadhaar-linked services all lean on OTPs to an Indian number. The portal has an official escape hatch for NRIs, but as you will see it is leaky, and Aadhaar-based verification routes straight back to your Aadhaar-linked Indian number with no alternative at all.

Here is the trap underneath all four. These systems do not warn you in advance and they do not share state. You can keep using your Indian credit card abroad in physical shops for months, never notice the number is dead, and then get blindsided the night you need to e-verify a tax return before the deadline. The failure is not gradual; it is a wall you hit at the worst moment.

The deadline that actually matters is the operator's, not the bank's

People worry about the bank freezing the account. That is rarely the immediate problem. The immediate problem is the telecom operator killing the number, because once the number is gone the OTP channel is gone with it, and recovering a reassigned number is impossible.

TRAI's rules, as they stand in 2026, give a prepaid number a finite life without a recharge. On Jio, Airtel and Vi the active window is about 90 days from your last recharge; let it pass and the number moves toward permanent disconnection. Airtel then adds roughly a 15-day grace period before the number is closed and released for reassignment. Vi requires a minimum recharge (as little as Rs 49) to keep going past the window. BSNL is the most forgiving, holding a number active for up to 180 days. There is also a quirk worth knowing: if your SIM still holds a prepaid balance of at least Rs 20 when the window expires, that Rs 20 is deducted to buy another 30 days, stretching the practical limit toward 120 days on the private operators. Do not rely on it; treat 90 days as the hard line.

The point that makes this urgent for NRIs specifically: a recharge done from a foreign app store or a foreign card sometimes fails, and you cannot receive the recharge-confirmation SMS if the number is already dark. So the safe move is not "recharge when it is about to expire", because by then you may not be able to. The safe move is to put a long-validity plan on the number while it is healthy and you are still able to transact.

What happens if you miss the window is the genuinely bad outcome. The number is reassigned to a new subscriber. Your bank now has a stranger's phone linked to your account, which is both a security hole and a lockout. Recovering from here is not a phone call. You generally have to visit an Indian bank branch in person or go through your bank's NRI re-KYC channel to register a new number, which can mean attestation, fresh documents and weeks of delay. This is the same re-KYC machinery covered in NRI account KYC re-verification, and it is far more painful than the Rs 3,000-odd a year it costs to avoid.

Keeping one Indian number alive, cheaply, from anywhere

The cleanest solution for most NRIs is the unglamorous one: keep exactly one Indian number permanently alive as your OTP number, and stop worrying about the rest. You do not need data, you do not need calls, you need the number to exist and to receive incoming SMS. Here is how to do that without overpaying.

The cheapest possible approach is the annual or long-validity recharge. On Jio the long-validity packs run around Rs 3,359 for a year of full service; Airtel and Vi have comparable annual plans in the Rs 2,999 to Rs 3,599 range depending on circle. That single recharge keeps the number active for twelve months, well past the 90-day disconnection line, with no monthly babysitting. For a number whose only job is to receive OTPs, this is the floor cost of staying banked in India, and it is trivial against what a re-KYC costs in time. There is a tempting cheaper option, the Rs 20-for-30-days minimum-balance trick under TRAI's retention scheme, but it keeps the SIM merely "active" without enabling SMS and calls reliably, so it is the wrong tool for OTPs. Pay for a real long-validity plan.

The mistake here is keeping the SIM in a drawer in India. A physical SIM left at your parents' home does nothing for you in London, because the OTP arrives on a handset you cannot read. You have two ways to actually receive those messages abroad.

The first is to convert the number to an eSIM and load it onto the phone in your pocket. Call or message your Indian operator, ask them to convert the physical SIM to an eSIM, and they send a QR code you scan. Modern phones run one physical SIM plus one or more eSIMs at once, so your Indian number sits alongside your local foreign SIM and quietly receives Indian OTPs while your foreign line handles daily life. This is the single best setup for most NRIs because the number genuinely travels with you and incoming SMS is the most reliable thing on a roaming connection.

The second is to put the number on international roaming so it picks up SMS on foreign networks. The catch is cost and activation. A regular Indian prepaid plan will not connect to a foreign network at all; you must activate an international-roaming pack first, and these are not cheap. As of 2026, Airtel charges around Rs 2,997 for a 10-day Europe pack and Rs 4,499 for a 30-day global pack, Jio Global is around Rs 2,799 for a 10-day Europe pack, and Vi's i-Roam packs sit near Rs 3,799 for 10 days. Those are holiday-trip prices, not a permanent solution; nobody keeps a rolling roaming pack live for years.

Put the numbers on it for a typical reader. Priya, in Dubai, needs her Indian number purely for bank and card OTPs. She converts it to an eSIM, drops it onto her iPhone next to her UAE Etisalat line, and puts a Jio annual long-validity recharge of about Rs 3,359 on it. Her all-in cost is roughly Rs 3,359 for the year, or about Rs 280 a month, and every Indian OTP lands on the phone she already carries. Had she instead relied on international roaming to receive those same OTPs, even a single 30-day Airtel global pack at Rs 4,499 would cost more than her entire annual plan for one month of coverage. The eSIM-plus-annual-recharge combination is not just convenient, it is the cheapest reliable option by a wide margin, and it is what I would do for almost any NRI whose bank still insists on an Indian-number OTP.

Registering a foreign number, where your bank actually allows it

The better long-term answer, when it works, is to make your foreign number the registered number so OTPs and UPI come to your everyday phone with no Indian SIM at all. The rules have genuinely moved in the NRI's favour here, but the rollout is patchy and honesty matters more than optimism.

On UPI the change is real and worth using. NPCI now permits UPI linked to an NRE or NRO account using an international mobile number, for residents of roughly twelve countries: Australia, Canada, Hong Kong, Oman, Qatar, Saudi Arabia, Singapore, the UAE, the UK, the USA, France and Malaysia. The number must be registered as the primary mobile on your NRE or NRO account with the bank. This means a UAE-based NRI can run UPI for Indian merchant payments and family transfers from a +971 number, no Indian SIM in the loop. IDFC First moved early and aggressively on this, ICICI confirmed support, HDFC is live in ten of the twelve countries, and SBI in eight of the twelve as of 2026, with Axis and others in slower, more limited rollouts. The practical guidance: this is a per-bank, per-country feature, not a blanket RBI switch, so the only reliable answer is to check your specific bank for your specific country of residence rather than trust a general claim.

The harder, older problem is net-banking and card OTPs to a foreign number, and here the picture is more honest than the marketing suggests. Many Indian banks will let you record an international number on your NRE or NRO profile, but a lot of legacy net-banking and card-issuing systems were never built to store a country code or to route SMS to a foreign carrier reliably. So you can have a foreign number sitting in your profile and still find the actual OTP never arrives, or arrives hours late, or fails on a particular transaction type. The banks that handle this best are the ones that have rebuilt NRI digital banking around international numbers, and the difference between them is large enough that it should influence where you keep your primary NRI relationship; that is exactly the lens in digital banking access for NRIs.

This is where banks genuinely differ, so do not assume your bank behaves like your friend's. Run a small test the moment you set a foreign number: attempt a low-value transfer or a card payment that triggers an OTP and confirm it actually lands on your foreign phone, on the right transaction type, in a usable time. If it does, you can lean on the foreign number. If it does not, you have learned cheaply that you still need the live Indian eSIM as your real OTP channel, and you have learned it before a large or time-sensitive transaction taught you the hard way.

There is a setup point that trips people up. To register a foreign number against an NRE or NRO account, the bank usually wants the account correctly flagged as non-resident and the number updated through the NRI channel, not the ordinary "change mobile number" flow, which itself often demands an OTP to your old, possibly dead, Indian number. If you are mid-migration and your Indian number still works, change it now while you can still receive that confirming OTP; doing it after the number dies is the chicken-and-egg trap that forces a branch visit. Get the account opened and flagged correctly from the start using open an NRE or NRO account from abroad.

The income-tax portal is its own separate trap

NRIs assume that if their bank OTP works, the tax portal will too. It is a different system with different rules, and it fails in its own way, so treat it as a separate problem.

The official position is generous on paper. The e-filing portal lets you register with a foreign mobile number, and for taxpayers flagged as Foreign or NRI it accepts email-OTP validation alone, meaning you do not strictly need an Indian SMS OTP to register or log in. That is the rule, and it is the rule you should plan around: make your email the primary verification channel on the portal.

The practice is leakier. NRIs regularly report that OTPs to US, UK and UAE numbers simply never arrive, because the portal mishandles country codes the same way old bank systems do. A workaround that has worked for some is to select the correct country from the dropdown in the contact-details screen and enter the number with its country code, after which the OTP sometimes comes through; but "sometimes" is not a plan. The dependable plan is email OTP for portal access, full stop.

The deeper trap is e-verification of the return itself, which is a distinct step from logging in. Filing the ITR is not complete until you e-verify it, and the cleanest e-verification methods are Aadhaar OTP and net-banking EVC. Aadhaar OTP goes to your Aadhaar-linked Indian mobile number, with no foreign-number option at all. Net-banking EVC routes you through your bank, which loops you straight back into the bank-OTP question above. So if both your Aadhaar-linked number and your bank number are dead, you can find yourself able to prepare and submit a return but unable to verify it, which means it does not count and you can miss the deadline by default. This is the single strongest reason to keep one Indian number, ideally your Aadhaar-linked one, alive even if your bank accepts a foreign number for everything else. The filing mechanics and verification options are laid out in ITR filing for NRIs, AY 2026-27.

Put it together for a concrete case. Arjun in the US registered on the portal with his US number, the OTP never came, and he fell back to email OTP to log in, which worked. He prepared his return, then hit the e-verify step, chose Aadhaar OTP out of habit, and it failed because the Aadhaar-linked Indian number was disconnected eight months earlier. With the deadline two days out, his only remaining path was net-banking EVC, which itself needed a working bank OTP. Because he had kept one Indian eSIM alive for his bank, that path worked and the return was verified with a day to spare. Had he let every Indian number lapse, he would have been reduced to sending a signed ITR-V by post to Bengaluru and praying it arrived in time. One live number was the difference between e-verified and not filed.

A pre-departure and standing checklist

The fixes above only help if you set them up before the number dies, which usually means before you fly or in the first weeks abroad while your Indian SIM still works. Treat this as a one-time setup plus an annual reminder.

Action	When	Why it matters
Put a long-validity or annual recharge on your OTP number	Before you fly, or now	Beats the 90-day disconnection line; an annual Jio pack is about Rs 3,359
Convert that number to an eSIM and load it on your travel phone	Before you fly	The number travels with you; incoming SMS is the most reliable roaming feature
Set a calendar reminder for the recharge expiry	At setup	A reassigned number means re-KYC, not a phone call
Register your foreign number for UPI where your bank and country qualify	First weeks abroad	Removes UPI's dependence on an Indian SIM for the 12 supported countries
Update your bank profile to your foreign number, then test an OTP transaction	While your old number still works	Avoids the chicken-and-egg lockout; confirms the foreign number actually receives OTPs
Set email as the primary verification on the income-tax portal	Anytime	NRIs can verify by email OTP alone; do not depend on SMS to a foreign number
Keep your Aadhaar-linked Indian number alive specifically	Ongoing	Aadhaar-OTP e-verification has no foreign-number fallback
Enable any app-based or push OTP your bank offers (for example SBI Secure OTP)	First weeks abroad	App-generated OTPs work over Wi-Fi or data, no SMS needed
Note your net-banking EVC and bank-OTP path as a backup	At setup	Your fallback for tax e-verification if Aadhaar OTP fails

Two of these deserve emphasis. The app-based OTP route is underused: several banks offer a soft-token app that generates the OTP on the phone itself over Wi-Fi, with no SMS at all. SBI's Secure OTP app replaces SMS OTPs for internet-banking transactions and works on a data or Wi-Fi connection, and ICICI's iMobile and HDFC's app support push-based approvals that can sidestep SMS entirely. Enable these while you can, because an app OTP that works over hotel Wi-Fi is immune to the dead-SIM problem altogether. And the "test an OTP transaction" step is the one people skip and regret; a five-rupee transfer that confirms your OTP channel works is worth more than any assurance from a call-centre script.

Edge cases

The number is already dead and reassigned. If your Indian number has been disconnected long enough to be reassigned, there is no recovering it; assume a stranger now holds it. Your route back is the bank's NRI re-KYC channel or, in the worst cases, an in-person branch visit on your next India trip to register a fresh number. Do not attempt to "reclaim" the old number; it is gone. Plan the re-KYC the way NRI account KYC re-verification describes, and on your next visit set up the eSIM-plus-annual-recharge combination so it never recurs.

Postpaid versus prepaid for the OTP number. A postpaid connection will not silently lapse for non-recharge the way prepaid does, but it bills you monthly whether or not you use it and is harder to manage on autopay from a foreign card. For a number whose only job is OTPs, a prepaid line on a long-validity annual pack is cheaper and simpler than carrying a postpaid plan you never call from. Keep postpaid only if it is already your Aadhaar-linked number and switching would trigger fresh KYC headaches.

Dual-SIM phones and the wrong default. On a dual-SIM or eSIM phone, OTP SMS arrives on whichever line holds the Indian number, but some apps and some banks send the verification SMS expecting it to originate from a specific SIM, particularly during UPI registration. If UPI setup fails on a dual-SIM phone, check that the app is using the Indian line for outbound verification, or complete the registration on a phone with only that SIM active.

The UAE and the foreign-number question. UAE residents are well served on UPI because the UAE is on the supported-country list and several banks support +971 numbers, but they should still keep one Indian eSIM for net-banking OTPs and Aadhaar verification, because UPI coverage does not automatically mean net-banking-OTP coverage at the same bank. The country being "supported" is a UPI statement, not a guarantee across every channel.

The closing read

The honest read is that the Indian-mobile-OTP problem is not a hard problem, it is an easy problem that becomes an expensive one the moment you ignore it. The number is a single key to four separate locks, and it fails silently, so by the time you notice you are usually already locked out at a bad moment, with a tax deadline or a rate change on the line.

So for most NRIs the recommendation is concrete: keep exactly one Indian number alive, make it your Aadhaar-linked one if you can, convert it to an eSIM so it rides in the phone you actually carry, and put an annual long-validity recharge on it for roughly Rs 3,000 a year. That single move covers net banking, card OTPs and tax e-verification regardless of how patchy your bank's foreign-number support turns out to be. On top of that, register your foreign number for UPI if you live in one of the twelve supported countries and your bank allows it, set email as your primary verification on the tax portal, and enable your bank's app-based OTP so you have a Wi-Fi route that needs no SIM at all. Then test it once with a small transaction.

The exception worth naming is the NRI banking entirely with a bank that has fully rebuilt around international numbers, in a supported country, who genuinely receives every OTP on their foreign phone. That person can let the Indian SIM go, with one caveat: keep the Aadhaar-linked number alive anyway, because Aadhaar-OTP tax verification still has no foreign fallback. For everyone else, the Rs 3,000 a year is the cheapest insurance in your entire Indian financial life. Pay it before you fly, not after you are locked out.

Related guides

• Digital banking access for NRIs
• NRE, NRO and FCNR accounts explained
• Open an NRE or NRO account from abroad
• NRI account KYC re-verification
• ITR filing for NRIs: AY 2026-27
• All Banking guides
• All Taxation guides

This guide is educational and general in nature. It is not individual financial or tax advice. Telecom validity rules, bank policies on international numbers and the income-tax portal's behaviour change frequently and differ by operator, bank and country, so confirm the current position with your specific operator, bank and a qualified adviser before relying on any single channel.