AT&T's chances of completing its $39 billion acquisition of T-Mobile USA are quickly fading as regulatory opposition to the deal mounts and the wireless giant's efforts to keep the deal on track smell of desperation.

The merger, announced in March, has been in trouble since this summer when the U.S. Department of Justice sued AT&T to block the deal. But things got uglier last week when the Federal Communications Commission said it would try to block the deal. Even though AT&T has vowed to fight on, it looks like the company is preparing for the worst.

In case you were in a turkey-induced coma over the long weekend, we offer this FAQ to get you up to speed on what happened and what it all means.

What exactly happened last week? I was elbow-deep in stuffing and gravy and missed all the action.

On Tuesday, the FCC said it didn't think the merger was in the public interest, and chairman Julius Genachowski asked the other four FCC commissioners to refer the case to an administrative law judge. Should they do so, AT&T would have to defend itself against the FCC's assessment that the merger is not in the public interest.

Then in the wee hours of Thanksgiving morning, AT&T said it would take a $4 billion accounting charge in the fourth quarter to cover a breakup fee to T-Mobile should the deal fall apart.

AT&T and Deutsche Telecom, T-Mobile's parent company, also said they've temporarily withdrawn FCC requests to transfer T-Mobile's wireless spectrum licenses to AT&T. On Friday, Bloomberg reported that AT&T has kicked into desperation mode, and is now considering offering to divest as much as 40 percent of T-Mobile's assets to appease regulators.

Does this mean that the merger is dead? Not quite. AT&T still hopes to win regulatory approval from the Department of Justice. If it's able to strike a deal with the DOJ, it can then re-apply for the spectrum license transfer to the FCC.

So why did AT&T withdraw its FCC application?

AT&T says it did so in order to focus its legal attention on the DOJ's suit. The FCC, meanwhile, won't start its hearing until the DOJ suit is concluded. So it makes sense for AT&T to direct its efforts on resolving the antitrust concerns with the DOJ first.

Critics such as the advocacy groups Public Knowledge and the Media Access Project also charge that AT&T is withdrawing its application in order to win a favorable court ruling that would then "pressure" the FCC to approve the merger. The same groups have also requested the FCC to release the proposed order that would have triggered the administrative-court review.

AT&T says it's well within its rights to withdrawal its FCC application and that "the FCC has no right to stop us."

Why did AT&T have to set aside $4 billion?

When AT&T struck the deal with T-Mobile, it promised to pay Deutsche Telekom $3 billion in cash if the deal didn't get regulatory approval and to hand over another $3 billion to $4 billion in assets if the deal fell through. AT&T's $4 billion charge serves to acknowledge that the deal might not get done as quickly at the company had planned.

AT&T initially said it planned to close the deal in the first quarter of 2012. Earlier this month, it said it expected to close it in the first half of 2012. Now it looks all-but-certain that it will be pushed out even further, if it gets approved at all.

Why do the Department of Justice and FCC oppose the deal?

While these agencies perform independent due diligence on mergers, they are essentially looking at very similar things. And in this case, both have concluded that the merger would leave the wireless market too concentrated. The FCC, for instance, said it had concerns about competition being harmed in 99 out of 100 top U.S. markets.

DOJ and the FCC have also rejected AT&T's arguments that the merger will lead to a faster build out of next generation 4G LTE networks and more robust innovation in the market. And neither agency is buying AT&T's argument that the merger will create jobs.

What are AT&T's options now?

AT&T has said it will re-apply to the FCC for approval of the merger and the transfer of spectrum licenses once it gets antitrust issues worked out with the DOJ. But AT&T's chances of winning a case against the DOJ in court with its current deal are slim. So it's likely that AT&T is looking to compromise to get the deal done.

Last week, Bloomberg reported that AT&T is willing to give up as much as 40 percent of T-Mobile's assets to get the DOJ's approval for the deal. The idea is that AT&T could divest or sell off big chunks of T-Mobile's spectrum to competitors in an attempt to settle antitrust and anticompetitive concerns.

Given how concentrated the wireless market already is and the fact that AT&T is already the second largest player in that market, it's likely that even 40 percent divestiture won't be enough to satisfy federal regulators, Bloomberg sources say. In other words, AT&T's efforts are probably a long shot.

So what are the chances that AT&T will be able to get the deal closed?

When the deal was first announced, analysts. And most analysts pegged the chances of the deal getting the necessary approvals at about 50 percent. Since the DOJ filed its suit to block the merger in August, the odds have dropped considerably. And now that the FCC said it also opposes the merger, some analysts put the chances of getting the deal approved around 10 percent or less.

If the deal falls through, what will happen to T-Mobile?

Good question. My guess is that T-Mobile will eventually be sold to some other company, either as a whole or piece-by-piece, as Deutsche Telekom clearly wants out of the U.S. wireless market.

If the deal doesn't happen, T-Mobile will get $3 billion in cash and some wireless assets from AT&T. That could sweeten the pot for other potential bidders. For now, thought, both AT&T and T-Mobile say they are committed to getting this done, because--well, because they have to. It's either that or give up the merger.

So in either case, it looks like at least some of T-Mobile's assets will have to be sold to a company other than AT&T. Is that correct? Who might be interested in them?

That is correct. As things look right now, some other company will likely have to buy some, if not all, of T-Mobile's assets.

Cable companies such as Comcast, Time Warner, and Cox Communications could be interested in striking some kind of deal with T-Mobile. These cable operators bought a significant amount of wireless spectrum in the 2006 AWS spectrum auction under the name Spectrum Co. This is the same auction in which T-Mobile bought the spectrum it's currently using for its 3G and HSPA+ network.

These cable companies have been looking for a way into the wireless market for years. So there's a chance that they could either buy T-Mobile or partner with it to combine spectrum assets. Some of these same cable providers tried something similar a few years ago. They teamed up with Sprint and formed a joint venture called Pivot. But the service never got off the ground.

Since then Comcast and Time Warner have kept mum about their plans for the spectrum they now own, but they have invested in Clearwire, a wireless provider building a nationwide 4G network. Cox Communications had plans to use its spectrum to build its own wireless network, but it has since abandoned that plan. And the company is no longer offering a wireless service.

Satellite TV provider Dish Network might also be on the prowl. Last summer, Dish bought satellite operators TerreStar and DBSD, which had been in bankruptcy court. It plans to use the spectrum licenses from these companies to operate a 4G LTE wireless network.

Other potential bidders for the T-Mobile spectrum include smaller cellular providers, such as MetroPCS and Leap Wireless.

What about Sprint Nextel? Why isn't it a likely candidate?

Sprint might be able to get its hands on some wireless spectrum if AT&T is divesting some of it. But it's unlikely. Sprint has enough spectrum, and it, so I doubt it would try to help AT&T find a suitable solution to its antitrust issues. And if the AT&T deal fell apart, I still don't think Sprint could buy T-Mobile, because it would be hard for the DOJ and the FCC to allow another major U.S. wireless operator to buy T-Mobile spectrum or assets, given the fact that they rejected AT&T's bid. Besides, you could expect AT&T to fight any such deal tooth and nail.

So what does all of this mean for current T-Mobile subscribers? Should T-Mobile subscribers move onto another service provider?

I don't see anything changing at T-Mobile for at least a year. There are several things that could happen and none of them will resolve T-Mobile's fate quickly.

AT&T could abandon its plans to buy T-Mobile. If this happens, T-Mobile will continue to operate as it has until Deutsche Telekom figures out what to do with it. Even if new buyers were found, they'd also have to go through a similar regulatory approval process by both the DOJ and FCC.

If AT&T chooses to continue to fight for T-Mobile, the issue could be tied up in the courts for a while. AT&T's $4 billion charge is a good indication that the company recognizes it won't be able to meet its original targets in terms of timing.

And if AT&T is able to strike a deal with the Department of Justice, there will be a process in which the divested assets are sold off. And the FCC will also have to vet and approve the license transfers to other service providers.

In other words, so far as the average consumer is concerned, nothing is likely to change for at least a year. Even though Deutsche Telekom doesn't seem to want to stay in the U.S. wireless market, the company has incentive to keep T-Mobile healthy enough to sell to other players. This means that T-Mobile is likely to get more aggressive in its offers to stay competitive. And it may be looking for other ways to differentiate its service.

We've already started seeing this. Earlier this month, T-Mobile announced a partnership with Google for its cloud-based music service. T-Mobile will be offering free music from Google to its subscribers, as well as carrier-billing support for those purchasing music through the service.

Still, T-Mobile is the only major carrier without the Apple iPhone. And that could turn out to be a major handicap.

If you're already a satisfied T-Mobile customer, I wouldn't switch because you're worried about the outcome of this merger. Whatever happens, it won't happen quickly. So my advice is to stick with it as long as you can.

Similarly, if you're considering signing up as a new T-Mobile customer, I'd say go for it. You'll likely be at least halfway through your contract before any assets change hands. And then whoever buys the wireless spectrum will have to figure out what to do with it. So if T-Mobile offers you what you need where you live and work, and you're able to find a good deal on the service on a phone you like, then you might as well take advantage of the competitive pricing while you can.

What about AT&T subscribers? Will any of this affect them?

I never believed that this merger would have much effect on AT&T subscribers. Down the road it might have helped with AT&T's network congestion issues. But even if the deal falls apart, AT&T will find another way to handle its spectrum issues. Perhaps it will speed up its migration to 4G LTE or it will rely more on Wi-Fi to alleviate congestion. Or it may even be able to acquire more spectrum in new spectrum auctions.