T-Mobile is having a sale! "Magenta Saturday" is one day only, this Saturday, November 19th. You will save money, but it's complicated. Pay attention.

T-Mobile has two totally different sets of plans. There's "Classic Unlimited," which is a regular cell phone plan. You get a two year contract with a subsidized phone. Then there's the "Unlimited Value Plan" which is usually about $20 cheaper a month, but they don't subsidize your device.

On "Magenta Saturday" they will give you a mail-in rebate for a phone or tablet on an Unlimited Value Plan, and they will add the balance of the device cost to your bill, split up over 20 months.

Here's the full chart:

"Equipment Installment Plans: On approved credit and 0 percent APR. Down payment and unfinanced portion required at purchase. Remaining balance paid in 20 monthly installments. Total post-rebate price of each device equals down payment amount plus monthly payment amount times 20."

So, lets examine the GSII. It's $49.99 up front for the phone, after rebate, and they tack $20 a month onto your bill, which is $20 a month cheaper than a regular plan, for 20 months. That covers the rest of the phone cost. If you stick out the 2 year contact for the full 24 months you end up with a $20 a month savings in the last 4 months, plus, of course, the rebate.

Still with me? Maybe this will help:

$220 SGSII after rebate + $80 "Classic Unlimited" plan over 24 months: $2140

$50 SGSII after rebate + $60 "Unlimited Value" plan over 24 months + $20 a month for 20 months: $1890

So eventually, somewhere, somehow, you will get $250 off the life of a GSII if you stick it out for 24 months. Cleared up now? Whew.

You can see my earlier failure in its full glory below. Sorry. And thanks, commenters, for the corrections.

Public Service Announcement: If you happen to be walking by a T-Mobile store this Saturday and see something about a "Magenta Saturday Sale," keep walking.

This hit our inbox today:

“T-Mobile wants to take the hassle out of Black Friday shopping with ‘Magenta Saturday’ by providing consumers with great deals a week early ― and without having to wait in line early in the morning,” said John Clelland, senior vice president of marketing, T-Mobile USA.

That's really sweet and all, but there aren't actually any "great deals" here. This is a straight up ripoff. Check out the included table and fine print:

[see chart, above]

"Equipment Installment Plans: On approved credit and 0 percent APR. Down payment and unfinanced portion required at purchase. Remaining balance paid in 20 monthly installments. Total post-rebate price of each device equals down payment amount plus monthly payment amount times 20."

This isn't a sale, this is a monthly payment plan for your phone. The GSII, for instance, will cost you $200 down (net down payment + rebate), plus $20 a month for 20 months, minus the $150 rebate. That's a total of $450, on a two year contract. You can get a GSII from T-mo's website right now for 0 (after rebate).

How is that a "great deal" or even close to the kind of deals people expect on Black Friday? The other phones are similarly ridiculously expensive. You can gasp at the other crazy prices on their website.

What's your deal, T-Mobile? If your in-store advertising is anything like your press release, you are seriously misleading your customers. A $230 markup is not a sale. Not cool.

T-Mobile to Hold “Magenta Saturday” Sale With Smartphones and Tablets for as Little as $0–$49.99 Net Down

On Nov. 19, T-Mobile will help holiday shoppers escape the dark lines of Black Friday and help them step up to data and the smartphone revolution with minimal upfront cost.

BELLEVUE, Wash. — Nov. 15, 2011 — On Saturday, Nov. 19, T-Mobile USA, Inc. will celebrate its “Magenta Saturday” sale. For one day only, consumers will have the opportunity to purchase any smartphone or select mobile broadband device, including two featured tablets ― the Dell™ Streak™ 7 or T-Mobile G-Slate ― for a net down payment of $49.99 (U.S.) or less after a mail-in rebate card.

New customers will be eligible for this deal when they sign up for a qualifying two-year agreement on any of the company’s Unlimited Value™ plans with 2GB or higher of full-speed data, all running on America’s Largest 4G Network. Existing customers also have the opportunity to take advantage of this great offer if they are eligible for upgrade (18 months tenure or greater) and switch from a Classic to an eligible Value plan.

“T-Mobile wants to take the hassle out of Black Friday shopping with ‘Magenta Saturday’ by providing consumers with great deals a week early ― and without having to wait in line early in the morning,” said John Clelland, senior vice president of marketing, T-Mobile USA. “T-Mobile continues to make it easier for consumers to upgrade to 4G data and join the smartphone revolution by making our best devices more affordable and pairing them with some of the best value plans in the industry.”

In July, T-Mobile launched its featured Value plan on America’s Largest 4G Network, with unlimited talk, unlimited text and unlimited data ― with 2 GB of high-speed data ― for just $49.99 per line for two lines with a two-year contract agreement.

The following is a sample list of some of the premium devices available through the promotion at participating retail locations nationwide, including the new HTC Radar™ 4G, Samsung Galaxy S™ II, HTC Amaze™ 4G and T-Mobile G-Slate:

[see chart, above]

For more information about T-Mobile’s new unlimited Value plans and the “Magenta Saturday” sale, visithttp://deals.t-mobile.com/unlimited-value-plan.

T-Mobile’s HSPA+ 4G network not available everywhere. See coverage details at T-Mobile.com.

1Equipment Installment Plans: On approved credit and 0 percent APR. Down payment and unfinanced portion required at purchase. Remaining balance paid in 20 monthly installments. Total post-rebate price of each device equals down payment amount plus monthly payment amount times 20.

About T-Mobile USA:

Based in Bellevue, Wash., T-Mobile USA, Inc. is the U.S. wireless operation of Deutsche Telekom AG (OTCQX: DTEGY). By the end of the third quarter of 2011, approximately 129 million mobile customers were served by the mobile communication segments of the Deutsche Telekom group — 33.7 million by T-Mobile USA — all via a common technology platform based on GSM and UMTS and additionally HSPA+ 21/HSPA+ 42. T-Mobile USA’s wireless products and services help empower people to connect to those who matter most. Multiple independent research studies continue to rank T-Mobile USA among the highest in numerous regions throughout the U.S. in wireless customer care and call quality. For more information, please visit http://www.T-Mobile.com. T-Mobile is a federally registered trademark of Deutsche Telekom AG. For further information on Deutsche Telekom, please visitwww.telekom.de/investor-relations.