Granted, the "nickel and diming" of hotline numbers (1900, 0900, etc) was nowhere as bad as today's cash shops, but a lot of us simply forgot they were always hungry for all our money
Here's a bunch other hotline ads for you to peruse - https://www.retromags.com/gallery/category/1729-telephone-hotlines/
PS: I never understood these american numbers that used letters, how were you supposed to know what was the actual number?
Some games let you keep playing without the correct code... until the difficulty automatically ramped up to impossible levels.