Buy an iPhone in Apple store through installments

When you finance with Apple you take out a consumer loan with a bank Apple partners with. So for iPhone trade up program, if you pass a credit check, then Citizens One bank gives you a 24 month 0% interest loan. Citizens One pays Apple for your iPhone in full, and you pay back Citizens One bank for the loan (iPhone Upgrade Program Terms and Conditions).

Apple’s other regular finance deal (for any product) is through Barclay Bank, But is similar - up to an 18 month interest free consumer loan to you from the bank. (Apple Financing with Barclaycard Credit Card - Apple).

All carriers also offer installment plans directly with them. Your device will be locked to their network until paid off though, if that is an issue for you.

Yes, you can user the iPhone Upgrade Program or Special Financing to get the iPhone in installments.

Your Credit Card Company may also have some type of installment plan.

There are monthly payment options. See the following: Apple