How to Choose a Modem

Most internet service providers (ISPs) will rent you a modem, but you might save some money and upgrade your modem’s quality if you buy your own.

That said, it’s important to buy the right modem for your internet service. So before you click “Check out,” here’s what you should know.

1. Check compatibility with your ISP

This is the most important step of all: Check that your potential new modem is compatible with your ISP.

You’ll need a DOCSIS cable modem for any cable internet provider like Xfinity, Cox, or Spectrum, and a DSL modem for any provider that serves up a DSL connection, like CenturyLink, AT&T, and Windstream. (Note that AT&T no longer sells new DSL internet plans.)

For fiber internet, you’ll need what’s called an Optical Network Terminal (ONT), and it’s probably best to get this from your ISP.

  • Cable internet: DOCSIS cable modem
  • DSL internet: DSL modem
  • Fiber internet: Optical Network Terminal (ONT)
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What about satellite internet?
Your satellite internet provider should include a modem or modem-router combo with your dish and any other required equipment. And due to the unique requirements of satellite internet, it’s probably best to stick with what your ISP gives you.

That said, if your satellite internet is giving you trouble, restarting your modem or calling your ISP to request a new one could solve the issue.

Most ISPs also provide lists of compatible modems that you can reference before you buy your new equipment. Here are links to compatible equipment lists for some of the larger internet providers in the US.

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2. Consider how much you want to spend on a new modem

Modems can range in price anywhere from around $50 to $250 or more. In general, the more you spend, the better (and newer) features you get. But that’s not to say you can’t find a budget modem that optimizes your internet connection for the best speed.

You should also consider that buying your own modem is a larger up-front cost, but it could save you a lot of money in the long run.

Equipment rental fees for internet providers can total up to $100 to $200 a year, depending on your provider. So after two years, you’ve either saved a considerable amount of money or you’ve broke even.

But even if your ISP throws in a modem for free, you may end up with a better deal if you buy your own. Some ISP-provided equipment is notoriously lackluster, and paying for better quality is likely worth it.

3. Make sure your modem supports your internet speed

One other key feature to pay attention to when modem shopping is what internet speed the equipment supports.

There’s no sense in paying your internet company for 500 Mbps speeds when your modem can support only 100 Mbps speeds. That means you won’t see speeds above 100 Mbps—and in essence, you’re paying for nothing.

At the same time, you don’t need to dig hundreds of dollars out of your wallet for a modem that supports gig speeds if you’re paying for only 100 Mbps. Again, you won’t see speeds much higher than 100 Mbps.

If you’re not sure what internet speed you’re paying for right now, you can run a quick internet speed test. The speed test will tell you your current download and upload speeds.

Keep in mind that these speeds likely fluctuate throughout the day and week, so you can run multiple speed tests and average them to get a more accurate idea of your internet speed.

4. What to know about cable modems

If you use a cable internet provider like Xfinity, Cox, or Spectrum, then you’ll need a special DOCSIS cable modem. An easy way to identify a cable modem is that it will have a place to connect a coaxial cable.

The back of the NETGEAR C 7000 cable modem


Get DOCSIS 3.0 or DOCSIS 3.1 protocol

DOCSIS stands for Data Over Cable Service Interface Specification and simply put, it allows your ISP to deliver cable internet to your modem and then to your devices.

DOCSIS 3.1 is the newest protocol, and it lets your modem handle gig (1,000 Mbps) internet speeds.

DOCSIS 3.1 modems tend to cost more, so if you’re not paying for gig speeds, you should be fine with DOCSIS 3.0.

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Thinking of DOCSIS 3.1? Tell your ISP.
If you’re eyeing a DOCSIS 3.1 modem, you’ll need to check with internet provider to make sure it supports DOCSIS 3.1 technology.

Take a look at channel bonding

Your cable modem also comes with channel bonding technology, which tells you how many channels the modem has for download and uploading data. The more channels it has, the more data that can travel between your devices and the modem.

Channel bonding is usually written out as two numbers, such as 24×8 or 8×4. The first number tells you how many channels are available to download data, while the second number tells you how many channels there are for uploading.

For example, a modem with 24×8 channel bonding has 24 channels ready to download data and 8 channels available to upload data.

If you guessed that more channels means faster downloads and uploads, you’re right. Of course, you’ll pay more money to get more channels. But, if you’re paying for faster internet speeds, you’ll want to make sure your new cable modem has enough channels so your speeds (and money) don’t go to waste.

5. What to know about DSL modems

Subscribe to a DSL internet provider, like CenturyLink or AT&T? Then you’ll need a special DSL modem. Here’s what you need to know before you bring one home.

Ask your ISP what DSL technology it uses

Not all DSL internet is the same, so it’s important to check in with your internet provider to see which generation it uses.

There are several different generations of DSL technology, so choosing a DSL modem that supports the specific technology your ISP uses is important.

Here’s a quick look at some of the different generations of DSL technology and the speeds each one supports.

  • ADSL: Up to 8 Mbps download speeds, 500 Kbps upload speeds
  • ADSL2+: Up to 24 Mbps download speeds, 1.4 Mbps upload speeds
  • VDSL2: Up to 50 Mbps download speeds, 15 Mbps upload speeds
  • GPON: Up to 2.4 Gbps download speeds, 1.2 Gbps upload speeds

Make sure it comes with an RJ11 phone jack

DSL uses your phone line to deliver internet to your house, so a modem with an RJ11 phone jack is crucial.

Make sure to check your new modem for a phone jack and Ethernet jack—at least one each. These can look similar, so modem makers often label them to show you the difference like on the CenturyLink Zyxel C1100Z modem below.

The back of a CenturyLink Zyxel DSL modem


Now that you know how to choose a modem, check these out next.

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Curious to know more about modems? We can help.

Should I get a modem-router combo?

A modem-router combo is a great way to save some shelf space and still route your internet connection to all your devices.

Sometimes modem-router combos are a little more expensive than a standalone modem or router, but keep in mind you’re still technically purchasing a piece of equipment that serves two different functions.

If you do choose a modem-router combo, check out our guide on what to look for in a router for some extra tips.

How do I set up my modem?

Most modems are easily set up by connecting it to your main computer or device, plugging in your DSL line or coaxial cable, and then plugging the modem into the nearest outlet.

If you’re running into trouble with your modem, check out our internet setup guide or visit your modem’s support site. Here are support portals for some common modem brands:

How do I keep my modem secure?

Because it connects to the internet, your modem can come down with a nasty case of malware or a virus just like your computer. Luckily, you can keep it safe with a few easy steps:

  1. Don’t use the default username and password for logging into your modem’s interface.
  2. Don’t use your modem brand, username, or password when you name your Wi-Fi network (this name is called an SSID).
  3. Do use encryption settings—preferably WPA2.
  4. Do keep your modem’s firmware updated.