IMPS turned a phone number into a bank address and settled interbank transfers in seconds

In 2010, sending money between Indian banks meant NEFT — settled in hourly batches, only during banking hours — or RTGS for large amounts. A worker wanting to send money home on a Sunday evening simply had no rail. Building a brand-new national real-time network bank by bank would have taken years.

NPCI's answer, publicly launched on 22 November 2010 by RBI Deputy Governor Shyamala Gopinath after a pilot with SBI, Bank of India, Union Bank and ICICI Bank, was the Interbank Mobile Payment Service. The clever engineering choice was to run it over the National Financial Switch — the interbank ATM network NPCI already operated — so member banks plugged into rails they were already connected to.

The clever product choice was the address: no account number, no IFSC code. Each customer got a 7-digit Mobile Money Identifier (MMID) from their bank, and a transfer needed just the beneficiary's mobile number and MMID — a vegetable vendor could display both at the shop. Confirmation came back by SMS within seconds, 24x7x365, from mobile, internet, ATM or branch channels.

IMPS became the template for everything after: instant confirmation, alias-based addressing and always-on settlement were carried into UPI in 2016. RBI raised the per-transaction limit from ₹2 lakh to ₹5 lakh in October 2021, and IMPS remains India's workhorse for instant account-to-account transfers.

Reuse the ATM switch; address payments by mobile number + MMID

Batch settlement in banking hours left evenings, weekends and holidays unserved — exactly when ordinary people send money.

The National Financial Switch already connected the banks, so real-time clearing could launch without new interbank infrastructure.

Mobile number plus MMID removed the account-number-and-IFSC friction that kept transfers a branch product.

Starting as a bank-led, RBI-supervised model gave it trust that wallet startups of the era lacked.

A new real-time rail doesn't need new plumbing: reusing an existing interbank switch cut build cost and let every member bank join fast. Aliases (phone numbers) beat account details for adoption.

IMPS proved India would use instant payments at scale, and its design — alias addressing, instant SMS confirmation, 24x7 settlement — became the blueprint for UPI in 2016, which overtook it in volume. RBI doubled the IMPS limit to ₹5 lakh in 2021; the rail still processes hundreds of millions of transactions a month as the fallback and account-based complement to UPI.