The downside is the price. Installation fees and equipment are extra and can run into the hundreds of dollars. The disadvantages are a slower speed when you go on the Internet and it ties up the phone line while you're online. There are many local and national dial-up providers. Local providers tend to be less expensive.
National providers have the advantage of nationwide dial-up numbers.
That way, when you travel, you can access the Internet with your laptop computer, just like you do at home. If you try to turn the ads off, the program will disconnect. Some people use a free Internet service as a backup in case their primary Internet connection fails. You still have to pay an Internet provider that offers DSL-compatible service. With cable access, there are can be speed concerns.