n. The practice of adding an unexpected fee onto a person's phone bill.
2000
Wisconsin consumers complained less about slamming, the unauthorized switching of phone service to another provider, and cramming, the unauthorized addition of services to an account.
1997
The next big thing in telephone scams is cramming — unauthorized phone charges, often for services customers never receive, from companies they've never heard of.
1997 (earliest)
Call it 'cramming,' 'whamming' or 'super-slamming.' Call it what you will, but Lorraine Parker calls it a ripoff. Parker was shocked recently to find charges crammed deep into her phone bill for services she says she didn't authorize.
Of the three terms listed in the earliest citation, the usage marketplace seems to have decreed cramming the winner over whamming and super-slamming. That makes linguistic sense because this practice involves stuffing bogus charges onto otherwise-innocent phone bills, and stuff and cram are synonymous verbs.