Comment by 1116574
9 hours ago
Back in the day you could send logos, ringtones, and bunch of other random crap thru carrier APIs, provided you signed a blood contract with them lol
Those APIs are probably still online, and still require to nail your ass to the contract, but technically I would assume it's possible.
Direct Carrier Billing is (was) also a thing. It had crazy silent mode where site can charge you (adding new item to your normal phone bill) just by serving special HTTP header - that your mobile internet provider picked up. As ripe for abuse as it sounds.