UK players have moved from phone bill deposits, which often had limits like £30...

https://planetfitnessprices.com/how-mobile-casino-deposits-have-evolved-from-phone-bills-to-instant-transfers/

UK players have moved from phone bill deposits, which often had limits like £30 per transaction, to Faster Payments and mobile wallets. These newer methods let you deposit as little as £10 quickly and securely, without waiting on phone carriers