Few things are as certain in life as the implementation of trade-in incentives on older model iPhones whenever a new version of the vaunted Apple smartphone is released. With Apple announcing the 4.7-inch screen iPhone 6 as well as the whopping 5.5-inch iPhone 6 Plus, the Apple faithful have come out in droves to upgrade to the new devices.

A number of options exist for the iPhone users who want to get their hands on the new gadgets. In her “Ask Maggie” column, CNET’s Marguerite Reardon concisely presents just about all of them – across the major carriers and online third-party sites.

Verizon Wireless and AT&T are running promotions through Sept. 30 in their brick-and-mortar and online portals in which older iPhones can be traded in, with the customer receiving a $200 gift card. While trading in an iPhone 3 or earlier may be a stretch – the iPhone 4, 4S, 5, 5C and 5S are all fair game, and the iPhone 5S will fetch a $300 gift card.

It should also be noted, perhaps ironically, that both of the leading carriers accept iPhones from any carrier, not just their own. Customers don’t necessarily need to sign another 2-year contract, according to a Verizon spokesperson, who told Reardon: “The trade-in promotion doesn’t apply to plans. If you pay full retail price for a phone, and you are an existing unlimited customer, you can keep your unlimited data plan.” AT&T’s promotion is more nuanced as customers who purchase any iPhone on AT&T’s early upgrade, no-contract Next plan can get $200 off – but only on a new iPad and that iPad must be purchased with a 2-year contract.

T-Mobile is simply offering to match any trade-in quote from AT&T, Verizon and Sprint – plus throw in another $50. There is no expiration date on the promotion but it is conceivably tied to the Sept. 30 date when AT&T and Verizon promotion ends.

Similar to T-Mobile, Sprint has a Buyback program that guarantees to beat competitors’ prices. The carrier is also offering an iPhone 6 $200 credit that essentially means customers can get a 16GB iPhone 6, subsidized to $199.99 – with a new or reneweed 2-year contract – for free, when they trade in an older iPhone model. That deal ends on Halloween.