Kyivstar Phone Registration? (Ukraine)

[RadioRaiders]

My friend in Ukraine who uses a Kyivstar pre-paid recently got a new phone. When he put his SIM in the new phone, he got a SMS from the network saying "Congratulations on your new phone! Please stop by any Kyivstar office to register it." And that as of next month all phones on their network must first be registered.

I've never heard of a GSM operator asking their customer to register their phone?

First I thought it may be in order to combat stolen phones. But then the operator can just make an IMEI blacklist and block the IMEI of any phone reported stolen. No "registration" by all customers would be needed for that.

Then I thought, since ~90% of SIMs in Ukraine are pre-paid, and can be bought without showing any ID, maybe Kyivstar realized they don't know who their customers are, and maybe want to tie some name/address to the accounts. But then they should be asking people to register their SIM cards, since that's their phone number.

...has anyone heard of an operator asking their customers to register their phone? ..and if so, for what reason?