There’s an old proverb that states, “There’s no such thing as a free lunch,” and in most instances, it holds true. You can’t get something for nothing. Cell phone carriers, for example, have started to offer unlimited data plans that seem to provide all the data you could ever want at no extra charge. Unfortunately, these companies use fine print and loopholes to skirt the definition of “unlimited.” Before you open your bill to find extra charges or use your phone only to find that it’s slower than dial-up, take the time to understand some of the details you need a magnifying glass to read.

Taxes, Fees, and More

The United States is one of the oddest countries in the world in that we don’t have straightforward pricing. From restaurants to cars to retail stores, you end up paying all kinds of sales taxes, municipal taxes, tips, and fees. The result can often push the price far higher than you anticipated. The bad news is that the same goes for your unlimited cell phone bills.

When you’re quoted a price from certain phone carriers, they leave out these taxes, fees, and other charges. The only way that people typically notice is when they get their first bill and find fees tacked on to the balance. When comparing phones, note that T-Mobile is the only major carrier that offers unlimited data without all the added costs. Get one line for $70 a month or four lines for $160, and that’s all you’ll pay.

Where You Can Use Your Data

When you’re comparing unlimited data plans, you should take a look at where you can use your data. Some service providers may require you to purchase additional plans to use data in Mexico and Canada, while others have limits or caps per day or month. If you go over the limit, you can incur heavy costs on some plans, so remain vigilant if your plan has these caveats.

Automatic Payment

One of the reasons why carriers can offer lower rates is because of automatic payments. By having your bank account information or credit card number, they know they’re always assured of their money each month. However, this also means that they want you to sign up for the service. If you don’t feel comfortable with that, you don’t have a credit card, or you don’t want auto pay for some other reason, expect to incur a fee of some kind each month. It’s not going to be enough to break the bank, but it definitely adds up over the course of a two-year contract.

Data “Limits”

Streaming music sucks down data so fast you wouldn’t believe. While this doesn’t seem like a problem with unlimited plans, carriers always have a cap or data limit. For most service providers, this cap starts at 22GB per month. Once you hit this amount, your speed usually slows from 5 to 12 Megabits per second (Mbps) to 3 Mbps. T-Mobile bumps the cap to 28GB per month, which is the best in the industry, giving you a bit more wiggle room on your usage without damaging your connection speed. For heavy users, the T-Mobile unlimited data plan seems much more beneficial and straightforward than the others.

Video Quality

If you’re a YouTube junkie, you might chew up tons of data in a short period of time. That’s what makes an unlimited plan so enticing. However, you should know that video quality and overall speeds can suffer. Most unlimited data plans restrict online videos at 480p, which is far below the 720p or 1080p you’ve grown to love on your laptop or home television. One positive is that T-Mobile plans to offer free high-definition streaming as part of its unlimited data package. This won’t improve the look of videos, but when you want to watch a movie on Netflix, it will be crystal clear.

Heavy data users will certainly find an unlimited plan comfortable and advantageous, but knowing the “limits” is something that everyone should do. Fine print is no longer fine print when it’s on your mind, and you’ll have better control of your usage each month.