Based on the given facts, it seems that both Teleline and AT&T are at fault for engaging in illegal gambling and misleading billing practices. Teleline ran an illegal gambling game, charging users a high rate per minute to participate. Meanwhile, AT&T listed the charges under a misleading heading on phone bills and displayed their name and logo on pages showing the charges. This could have led customers to believe that the charges were legitimate long-distance calls, rather than illegal gambling debts.
Regarding the question of whether the bills were so misleading as to constitute fraud, I believe that Kemp may have a case. According to the textbook principle of consumer protection, companies have a responsibility to provide accurate and clear information to consumers about the products and services they offer. If a company intentionally misleads consumers or provides unclear information, they may be liable for fraud or other legal consequences (Mallor et al., 2020, p. 418).
In this case, it seems that AT&T may have intentionally obscured the nature of the charges for Teleline's gambling game by listing them under "direct dialed calls" and displaying their name and logo on the billing pages. This could have led consumers like Kemp to believe that they were paying for legitimate long-distance calls, rather than illegal gambling debts. As a result, Kemp may have a valid claim for mail fraud against AT&T.
In terms of who should win in court, it's difficult to say for sure without more information about the specific laws and regulations governing this case. However, based on the facts presented, it seems that Kemp has a reasonable case against both Teleline and AT&T for engaging in illegal gambling and misleading billing practices.