Quite possibly. I have had the experience of activating a new prepaid sim a few years back and immediately receiving sms to say some subscription had been renewed. My first thought was that the dealer who sold me the sim pack had signed me up for this service, then I realised it was legacy from previous user of the number. Luckily I figured out how to cancel straightaway, but yeah not everyone would notice, maybe some wouldn't even read the sms.