> why not use that as the unique ID

Maybe I don't want to give people my phone number

Maybe I have multiple phones

Maybe I anticipate changing my phone number (maybe I hate my current carrier)

Maybe I want something easy for people to remember, or catchy "mybusinessname@mybank"

Forcing people to use a particular naming regime should only be done if there is a very compelling case for limiting your users

VPA is used for discoverability across UPI clients. Phone numbers can be used for discoverability among users of a single client. For eg: foobar@icici on Google Pay & baz@hdfc on PhonePe can transact with each other, but can't use phone numbers. But +91-1234567890 & +91-9876543210 can discover & transact only if they are both on either PhonePe or Google Pay or any other client application. QR Codes were initially client-specific too, but now they are scannable across apps.

UPI truly is a revolution. I can have a 6Rs chai tea (8 cents) from a road side tea stall and pay using UPI with zero transaction fees.

> UPI truly is a revolution. I can have a 6Rs chai tea (8 cents) from a road side tea stall and pay using UPI with zero transaction fees.

The main benefit of UPI is that it works really well for small amounts, e.g. the INR 6 tea. Such small transcations were traditionally too small/uneconomical for Visa/Mastercard.

However as the transaction size grows, say you're buying a laptop for INR 50,000 -- that's when the protections Visa/Mastercard build in against fraud start helping you and UPI's "no transaction fee" value proposition also starts looking like "no accountability".

Interestingly, India has a home-grown Visa/MC alternative called RuPay, which also waives transaction fees for small amounts and is a credible alternative to Visa/MC.

Unfortunately Indian startups have been obsessed with pushing e-wallets (PayTM et al) or direct electronic cash transfers (UPI) because it benefits them -- as the transaction size goes up it certainly doesn't protect the consumer.

You can have phone_number@paytm or phone_number@bank as you vpa is you prefer that, also UPI API, you can search users with phone number so if i want to send money to a friend and I know his no I can search his VPA/s

I use same phone number across multiple bank accounts. So I create unique UPI IDs to receive in each. So Google pay is linked to icici, Airtel is linked to Canara bank. When people send money, I receive it in the corresponding one.

With just phone number, I will need to get multiple sim cards for each bank account.

(User of both UPI and PayNow)

And UPI names are easier to remember than phone numbers. And you can change your phone numbers without any worries

Since that is the most obvious UX, most PSPs automatically assign you mobile@PSP.

However, VPA lookups are public (VPA->Name), so your mobile Numbers can now be used to get your real name, which resulted in a lot of backlash and PSPs making this an opt-out feature.

From my understanding, I think just your phone number/VPA is enough to send money. I am not sure how it works in practice but I assume the VPA concept is there so that your phone number is not exposed if you don't wish to.

This only works if both parties are on the same PSP and no VPA lookup over UPI is required. So if I am not registered on PhonePe, you can’t send me money using just my phone number there.

For other cases, most PSPs will automatically register mobile@psp for you with an opt-out.

VPA based on just the phone numbers may be convenient, it can lead to frauds. At least in India where - for most part - phone numbers aren’t treated like one’s personal data. Apps like Truecaller make it worse. Imagine receiving tons of involuntary charity requests on your UPI app, waiting for you to pay.

If not fraud, it will clutter the whole experience of UPI payments.

yes they can be used as well. In fact Phone number can be used to discover UPI ids connected to them and if user has signed up via NPCI app BHIM then <phone_number>@upi is a valid VPA.