Questions
answered.

*99# is India's USSD-based UPI service built by NPCI. It works without internet. You dial a code, your bank responds through SMS-style menus over the voice channel, and you reply to send money. Works on any phone with a basic cellular signal.

Not currently. Download the APK from GitHub releases, or use the PWA on any phone (Android or iOS) without sideloading.

No account, no email, no sign-up. Your bank account is already linked to *99# by NPCI when you set up UPI. OffPay is just the interface.

Airtel, Vodafone (Vi), and BSNL: yes. Jio: no. That's a Jio network-level constraint, not an OffPay limitation.

₹5,000 per transaction and ₹10,000 per day. These are NPCI-level limits for the *99# channel, not set by OffPay.

One-time setup to link your bank to the *99# channel. After this, OffPay handles everything. Done once, never again.

If you use BHIM as your UPI app, toggle on the *99# service in BHIM settings once.

Android's only public USSD API can't navigate multi-step menus. Accessibility Service lets OffPay automatically type your amount, UPI ID, and PIN into the carrier's dialog so you don't have to. If you'd rather not, use Manual mode: it just opens your dialer instead.

To programmatically initiate USSD calls to *99#. OffPay never places regular phone calls, only USSD requests to the carrier. It also reads the active SIM's carrier name to warn you if you're on Jio (where *99# is unsupported).

Since OffPay is sideloaded, Android 13+ blocks restricted settings like Accessibility by default. The fix: The setup video shows exactly where.

Your PIN is held in volatile memory only, masked as •••• in any logs, cleared within 500ms of session end, never persisted, and never shared. The app has no INTERNET permission and is structurally incapable of sending anything anywhere.

OffPay surfaces the carrier's exact error message. Common causes: wrong PIN, bank not linked to *99#, daily limit exceeded, wrong UPI ID, or weak signal. Tap the failed transaction in history to see the full reply and retry in one tap. A 25-second timeout prevents stuck sessions.

In Auto mode, OffPay paints a branded overlay over the system USSD dialog so you only ever see OffPay's UI during a session. We never see your PIN, as it's typed locally on your device, never stored, and never sent anywhere.

USSD (*99#) signaling occurs over the unencrypted GSM voice channel, meaning it is not encrypted end-to-end like HTTPS. This makes it theoretically vulnerable to carrier-level interception, SIM swapping, and base station spoofing (IMSI catchers). OffPay has no control over cellular protocol security; users should operate with normal cellular safety precautions.

In Manual Mode, OffPay copies details (like the recipient's UPI ID) to the system clipboard. If your device has malicious applications installed, they may perform clipboard hijacking to read or alter copied text. Always verify the recipient's name on the carrier's final confirmation screen before entering your PIN.

No. Since OffPay works entirely offline, it cannot monitor or block active screen recording, casting, or remote-desktop apps (AnyDesk, Zoom, TeamViewer). If you enter your PIN while sharing your screen, your PIN could be visually compromised. Ensure all sharing/recording is stopped before initiating a payment.

Custom Android distributions (like Xiaomi's HyperOS/MIUI, OPPO's ColorOS, or Vivo's Funtouch OS) modify the layout structure of system USSD dialogs. This can prevent the Accessibility Service from parsing the menus correctly in Auto Mode. If you experience issues, switch to Manual Mode in the app Settings to execute the transaction safely.