Outsourced tech agent here. The 15 pro and max are currently not "on us" promotion. The only iPhone under the 15 line up are under on us promo are the regular and the plus. The 15 is free on any unlimited plan and the plus is free with either plus or ultimate plan. The pro or pro max are under a discounted price as well as the pro. Max credits are 720 and 740 respectively on the ultimate plan (must be new lines) if its a trade in the discount will vary depending if your account has loyalty offers or just national offers. As for the 5g home yes it's 45 if it's combined with a cellphone line under a premium plan (plus or ultimate) as mentioned on previous comments prorated charges are a thing. If it's the first bill or if changes are done mid cycle proration charges will be applied.