The best money product I ever used had a scratch-off panel on the back.
I bought it at a sari-sari store in Cebu in January 2024, a cardboard card with a 14-digit code hidden under a patch of silver film. The shopkeeper’s daughter typed the code into my phone, my balance jumped from 12 pesos to 112, and the whole thing took about forty seconds. No app download, no signup form, and nobody asked what I planned to do with the credit.
That forty seconds taught me more about building money products than most of the whitepapers I’ve read since. Prepaid phone credit worked out balances, top-ups, and trust decades before crypto existed, and it did it for the exact customer base crypto still can’t reach.
The balance you can read at a glance
Dial *143# on a Philippine SIM and one number comes back: your load, in pesos. One number. Every call and text deducts at a visible rate, and when the balance hits zero, the phone stops making calls until you top up. There is no statement to reconcile and no quiet accrual to track.
My first Ethereum wallet showed me three tokens, eight decimal places, and a dollar estimate buried behind an extra tap. Sending $20 required a gas figure that moved while I watched it, and the final balance landed somewhere different from the preview. Prepaid got the hierarchy right: the balance is the product, and everything else is plumbing.
Back in 2012, over 90% of customers in India and Africa were on prepaid plans, and this design is a big reason why. A prepaid account is honest about its own state. It never displays a number it can’t honor.
Top-up happens where you buy bread
Refilling a prepaid phone is something you do while buying breakfast. In the Philippines and India, electronic reloading let anyone with a SIM become a load retailer, which is why credit sells in every neighborhood, however remote. In Kenya, Safaricom built a “Sambaza” feature so one phone could push airtime to another number, and carriers across the continent copied it under names like Me2U.
That ubiquity is the moat. M-Pesa launched on 6 March 2007 with 750 agents, and by 2010 it was moving transactions worth more than 30% of Kenya’s GDP each year. The account felt real to its users because every corner shop could fund it and pay it out.
Now compare the onboarding I watched a friend endure last year. Download the app, photograph an ID, wait a day for verification, wire money to an exchange, buy ETH, pay a withdrawal fee, then pick a network while a support article explains what a layer 2 is. His top-up took four days and three support tickets. Mine took forty seconds at a counter.
When airtime became money
Prepaid credit earned so much trust that it started behaving like currency. In Zimbabwe in 2012, with banks hollowed out and small change scarce, The Wall Street Journal reported on May 2, 2012 on how phone credit circulated at fixed denominations from 10 cents to $50. Shops accepted it because everyone had a use for it and everyone could verify it. Migrant workers in Europe and the Gulf still send international top-ups home as a form of support, a remittance that arrives as minutes.
Nobody drew up a plan to make airtime money. It became money because it split into small amounts, verified in seconds, redeemed for something everyone wanted, and stayed simple enough for a shopkeeper to explain in one sentence.
Three rules I keep on my desk
Show one balance in one unit. The moment a user has to convert between tokens, gas tokens, and dollars to know what they own, the product is asking them to do accounting it should do itself.
Make the top-up a place. Cash at a counter beat every onboarding flow I’ve designed. Meet users where their money already lives, in the amounts they already carry.
Keep denominations human. The 50-peso card exists because fifty pesos is what a person actually has in a pocket. Minimum deposits and fees priced in fractions of some token nobody asked for tax attention, and attention is the scarcest balance a user has.
A prepaid phone in 2007 could do something plenty of crypto wallets in 2026 still can’t: work for a person holding $3, a cheap handset, and no patience for jargon. The technology has traveled a long way since those silver scratch panels. The bar they set hasn’t moved at all.
