The new Apple Upgrade program includes a stipulation that users must connect to AT&T, T-Mobile, or Verizon when leasing an iPhone. John Gruber of Daring Fireball suggests this requirement stems from significant financial deals Apple has with these major carriers.

According to a former Apple employee, these agreements, worth "hundreds of millions of dollars," likely include this concession as part of a package deal. This exclusivity also serves as an incentive for smaller carriers to align with Apple's objectives.

Another contributing factor is fraud prevention. A former Apple Store employee noted a surge in fraudulent iPhone sales when carrier financing was first introduced. The activation requirement with major carriers helps mitigate this risk, as carriers have more advanced systems to detect and deter fraudulent activity, preventing losses they previously absorbed.

While enrollment requires a connection to one of the eligible carriers (prepaid plans are not permitted), Apple confirms that leased iPhones remain unlocked, allowing users to switch carriers at any time, subject to carrier terms.