*99# put every Indian bank inside a ₹1,000 feature phone, no internet needed

In 2012 India's mobile banking push was aimed at apps and SMS, but most of the country used basic feature phones with no data connection. Each bank that did offer USSD banking had its own code, available only on some operators — a patchwork that could never reach the unbanked.

Instead of letting banks fight operator by operator, NPCI got the Department of Telecommunications to allot a single national short code, *99#, in January 2012, and launched a USSD-based interbank mobile banking service in November 2012. Any customer of any participating bank could dial the same code on any telecom network and reach IMPS fund transfer, with balance enquiry and mini-statements to follow.

The cleverness is the channel choice: USSD travels on the GSM signalling path, not the data path, so it works on the cheapest handset with zero internet. And because NPCI — the banks' own shared utility — sat in the middle as the aggregation platform, banks joined one rail instead of negotiating with every operator.

The model later became the template for offline UPI: *99# was extended to UPI transactions, and NPCI's 2022 UPI123Pay picked up the same feature-phone constituency with IVR and missed calls.

One shared USSD code for all banks, no data plan required

Feature phones vastly outnumbered smartphones among the unbanked, and app-based banking simply didn't exist for them.

A single national short code replaced the per-bank, per-operator patchwork that made USSD banking unusable in practice.

NPCI's position as the banks' shared utility let it aggregate both sides — banks and telecom operators — into one rail.

USSD needs no data plan and no smartphone, so the marginal cost of reaching a rural customer was near zero.

When the device is the constraint, move the interface down the stack: USSD rides the signalling channel every GSM phone already has, so ubiquity itself becomes the distribution network.

*99# survived every smartphone wave as India's offline fallback: it was extended to UPI, listed among the channels in the World Bank's 2021 fast-payments case study of India, and complemented by UPI123Pay in 2022. The telco revenue-sharing disputes it triggered pushed TRAI to consult on capping USSD session charges at ₹1.50 in 2013.