FWIW, I personally refuse to do business with companies that utilize this kind of flow - it feels like a scummy dark pattern, where they're banking on people to forget they've signed up and they can get at least one month's worth of charge out of it. That goes double when you can sign up online but it requires calling in (and talking to "retention" people) to cancel.
"But we don't want to interrupt your service.." goes the salesman.. yeah right.
If you're going the free trial route, fine, but it should require affirmative action after the trial to begin billing. You don't need my credit card until I've actually bought something from you.