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What is a 3G Modem?

John Lister
John Lister

A 3G modem is a device that allows a computer to connect to the Internet via a high-speed mobile broadband connection. This means that the Internet signal is broadcast over the airwaves rather than sent and received through a cable or telephone line. The technology is largely the same that is used for delivering Internet content to modern cellphones.

There are a variety of broadcasting standards that are covered by the 3G title, which is short for the "third generation" of mobile technologies. The most common standards in the United States are UMTS and CDMA. Because the various standards are not always compatible with one another, users must check carefully that a 3G modem is compatible with the cell phone network from which they intend to get 3G service.

A 3G modem usually plugs into a USB port.
A 3G modem usually plugs into a USB port.

In most cases, a 3G modem will come as a plug-in device, often referred to as a dongle. This is usually plugs into a USB slot on a computer and closely resembles a portable memory drive. The device houses the antennae that receive the signal, the SIM card that authenticates the user to communicate on the network, and the modem itself, which converts the wireless information into data the computer can understand.

A 3G modem uses the same cell towers as modern smartphones.
A 3G modem uses the same cell towers as modern smartphones.

Some forms of 3G modem also work as a router, meaning they can share the signal with multiple devices. Some such routers are relatively large devices and include Ethernet slots for making a wired connection with a computers. Others are smaller and communicate with the computers via Wi-Fi. This can be a useful solution for portable devices that have a Wi-Fi connection but do not have a USB socket,

Some 3G modems allow for multiple wired connections.
Some 3G modems allow for multiple wired connections.

A 3G modem user will often have to be much more careful about their Internet use than somebody a landline or cable-based service. This is because there are usually much lower monthly limits on the data that can be downloaded. These can be as low as 250MB and rarely exceed 5 GB a month. A user who passes this limit may be cut off for the rest of the month, but could also be allowed to continue using the service and charged extremely high penalty fees for the additional data use.

In the 2010s, 3G networks began to be replaced with 4G networks.
In the 2010s, 3G networks began to be replaced with 4G networks.

There are also some 3G technologies that are designed to work primarily for desktop computers. One example is WiMax, which can be used by some homeowners as their primary internet connection. This is only really practical in areas that have strong WiMax coverage but where fixed line or cable services are either unavailable or prohibitively expensive.

Discussion Comments


The 3G modem has been wonderful for me. I travel a lot and take my laptop with me wherever I go. The mobility of this is what really sold me on it.

Being able to connect anywhere I am and know that I have a secure connection is a big plus. If I am traveling down the road while someone else is driving, I can get on the internet on my laptop.

When I am staying at a hotel, I can use my own secure connection with my 3G modem. No more using a slow hotel connection that might not be secure.

When I am at home, we can have up to three users online at the same time. This happens quite often, and I have never noticed any reduced speed with more than one person on line at the same time.


@myharley - If you spend most of your day on the computer, the GB limit is probably something you will want to consider.

When I bought my 3G modem, the guy at the store said most families should be able to use this all month and not go over the 5GB we are paying for.

5G might sound like a lot, but for a family, you can use this up in a hurry - especially if you download movies or like to watch TV online.

We pay $10 more a month for every GB over our 5GB limit. This is not a huge amount, but I get frustrated worrying about it all the time. Most months we go over this by at least 1GB.

Every time I get ready to download a book or video, I always wonder how much data I am using up.


@myharley - I can't speak for everyone, but I really love my 3G modem. Two of the biggest reasons are because of the questions you asked.

I have found the 3G modem to be quite a bit faster than my satellite connection. I know there are different levels of speed you can get with a satellite, so don't know how that compares for your situation.

I had the highest download speed, and the 3G modem is faster than that was. I am anxious to try out the 4G in the near future.

I also don't have nearly the connectivity issues with the 3G modem as I did with satellite. It seems like a few drops of rain or a little wind used to interfere with a strong signal with my satellite.

I haven't had any issues like with with the 3G modem and wish I had not waited so long to start using it.


My biggest hesitation about getting a 3G modem is the GB limit. I currently connect to the internet using satellite and have more bandwidth than I could ever use in a month.

Both my husband and I do most of our work from home on the computer, so this is an important thing for us to consider.

The satellite is nice because we live in a remote location that does not have a cable option. I have also been pretty pleased with the speed of the satellite connection.

Does anybody know how the speed of a 3G modem compares with something like a satellite internet connection?

Also, does the weather affect this connection at all? Sometimes bad weather has an adverse affect on my current internet connection.


@ddljohn-- My limit is 4GB per month. If I go overboard, I will have to pay extra fees as well. Thankfully, it hasn't happened so far. I can't watch videos or download anything large, but it's something I can live with. Most months I even have close to 1GB left over.

I think you should increase your limit if you can. If you get one with 4GB and 5GB, it should be plenty and you can probably download some things if you need to.

I have access everywhere, different companies might have different quality reception though. I completely agree that this is great for traveling. I went to my parent's house for a couple of weeks last month and just took my 3G modem with me. We don't need an actual modem box or land-line connections anymore, just the 3G usb modem.

The same is true for cell phones, but 3G modem plans tend to be cheaper than cell phone plans with internet access.


@burcidi-- What is your monthly limit on your modem?

I'm using a wireless 3G modem too and I have a 2GB monthly limit. It's not enough for me though. I have to be really careful with it and keep track of it all the time. I don't even do anything extra, other than check my email and surf the net. The first couple of months I went overboard and the fees were unbelievable.

I think this is good option for people who travel and need internet access on the go. But it's really not enough to use at home. There are also a couple of rooms in the house where the wireless access is not very good. I need to keep it in the living room for best access.

The only thing I do like about mine is that it lets both my wife and I connect at the same time. I think most modems don't offer that.


I've been using a 3G wireless modem to connect to the internet on my laptop for the past year. I'm really happy with it. I've been renting a room and since we are all renters here, the house I'm living in has not internet access. There are also no free Wi-Fi networks available nearby.

I was a little hesitant to get a 3D modem at first. I didn't know if the connection speed would be fast enough or how quickly I would use up my GB limit. However, it has worked out much better than I expected. I never have problems accessing the internet and the speed is really good.

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    • A 3G modem usually plugs into a USB port.
      By: akeeris
      A 3G modem usually plugs into a USB port.
    • A 3G modem uses the same cell towers as modern smartphones.
      By: Tonanakan
      A 3G modem uses the same cell towers as modern smartphones.
    • Some 3G modems allow for multiple wired connections.
      By: Zsolt Biczó
      Some 3G modems allow for multiple wired connections.
    • In the 2010s, 3G networks began to be replaced with 4G networks.
      By: Tarikh Jumeer
      In the 2010s, 3G networks began to be replaced with 4G networks.