Pay Monthly with Interest-Free Phone

Hi

I'm currently looking at upgrading my phone to a Samsung Galaxy S9+, by having a Pay Monthly $30 Carryover Plan and paying it off Interest Free via either a 12 Month or a 24Month Contract. When I get to the Cart (after adding the plan to my cart), it informs me that You can get a phone interest free on this plan, however when I go to the Samsung S9 or S9+ Page, it only offers it to me if i want a Monthly Plan of the below, with no option of the $30 Plan.

When I go to add it to my cart, the $30 Plan disappears and I can only choose from the selection of Plans in that screenshot.

Regardless of what i choose as the Initial Cost, the options remain the same.

Are Interest-Free Phones (with Pay Monthly) only available for the $40, $55, $70 & $129 Pay Monthly Plans???

Also (a Side Note), I see that $55 Pay Monthly Plan is repeated twice on that Screen.

Thanks in Advance