How to Use Your Cell Phone as a Modem

One of the most common questions asked about mobile computing is how to connect a cell phone to a laptop for Internet access. Although tethering isn't very difficult to accomplish, the answer is a bit tricky because wireless carriers have different rules and plans for allowing (or not allowing) tethering, and cell phone models also have different limitations. When in doubt, it's always best to refer to your service provider and handset manufacturer for instructions, but here's some information just to get you started.

What You Need

To use your cell phone as a modem, you need the following:

The device you want to be able to go online with, of course (i.e., your laptop or tablet)
A data-capable cell phone that you'll use as the modem (i.e., the cell phone should be able to go online on its own)
A data plan for the phone from your wireless provider. Most cellular providers these days require you to have a data plan for your smartphone anyway, but regular (or feature) phones may also be web-capable and therefore can also act as modems for your laptop. You'll need to have a data plan for the phone, whether it's a cell phone or smartphone.

Tethering Options

There are a few ways to use tethering so you can go online from your laptop (or tablet) using your cell phone's data plan.

Tethering plans from your wireless carrier: This is the official way to get tethering. The major wireless providers (AT&T, Verizon, Sprint, and T-Mobile) require you to have data plans that cover tethering or sign up for a separate hotspot plan. Once you've signed up for one of these plans, you can connect over bluetooth, Wi-Fi, or USB (see the links below for instructions for your carrier).

Apps: There are several mobile apps for tethering Android and other smartphones; some are free, with full versions of these apps priced $10 and $30. For that price you get an easy way to connect your laptop to your smartphone over USB or bluetooth and use your smartphone's data service on your computer, bypassing carrier tethering fees perhaps. PdaNet is a popular tethering app for most platforms, and we have step-by-step instructions for tethering your Android phone to your laptop.

Jailbreaking for iPhone users: Apple pulls tethering apps from the iTunes store, but users who don't mind bending the rules can jailbreak their iPhones to use PdaNet too.

Tethering Instructions by Wireless Carrier

Find your provider below to get information on whether they allow tethering and how much it costs. If you're in the market for new cell phone service, read through all the profiles to find out which cell phone company is the most flexible when it comes to tethering.

AT&T has one of the most thorough websites with a section on wireless laptop solutions as well as information on tethering handsets.

What You Need To Tether an AT&T Cell Phone

You can tether your AT&T iPhone or most other types of cell phones. To get started using your AT&T cell phone as a modem for your laptop or tablet:

Check if your cell phone is in the list of LaptopConnect compatible cell phones.
Updated AT&T data plans: Starting June 7, 2010, AT&T is allowing tethering on its new DataPro plans only, for $20 extra a month, but this does not include additional data usage—data accessed from your laptop count as part of the DataPro's 2GB limit.
"Grandfathered" customers who had a DataConnect Plan may be able to keep their existing tethering service, which starts at $20 for light users and goes up to $60 for 5GB of monthly usage (similar to AT&T's mobile broadband plans that allow laptop users to directly connect to the Internet using a network card).
AT&T has a comparison chart of available rate plans for you to compare options. Note that the DataConnect plans are in addition to data plans needed for your smartphone or PDA and the amount of data you can access with the plan is limited, so tethering can be pricey.

To tether your cell phone to your laptop, you can use either bluetooth (if your laptop and cell phone are both bluetooth-capable) or a cable (USB or serial), depending on your particular phone.
Finally, you also need to install AT&T's Communication Manager software on your laptop; the software is also only compatible with Windows, though.

Once you have all these things in place, you can use AT&T's software on your laptop to initiate the connection to your cell phone and use it as a modem for going online. Be aware while you are using the service, though, of that data cap. You don't want to go over the limit and find huge fees on your next bill!