Home > Articles > Networking

DSL FAQs

Telecommunicatons expert Annabel Dodd provides an overview of DSL: who sells it, how it works, and how residential and commercial DSL services differ.

Telecommunicatons expert Annabel Dodd provides an overview of DSL: who sells it, how it works, and how residential and commercial DSL services differ.

The growth of the Internet and the proliferation of powerful computers have created a demand for lower-cost, high-speed remote access to corporations and the Internet. High-speed services such as T1 are affordable for large and midsize organizations. But until the advent of DSL, teleworkers, small businesses, and branch offices of large companies were largely left out of the loop.

Small and medium-sized companies as well as residential consumers buy DSL for Internet access. Businesses purchase it as a lower-cost alternative to T1 service. DSL works over the same copper already installed by telephone companies for voice traffic. Consumers want it because it is "always on" and is faster than dial-up services such as those sold by AOL. DSL is an alternative for residential customers to cable TV modems.

What Is DSL Service?

Digital Subscriber Line (DSL) service is a high-speed digital service that works on the same copper cabling used for voice. Telephone companies, Internet service providers such as EarthLink, and competitive local exchange carriers (CLECs) sell it. There are many flavors of DSL, including asymmetric DSL (ADSL) and symmetric DSL(SDSL), which are described in this article.

What type of DSL service do incumbent local telephone companies sell?

Local telcos such as Verizon (formerly Bell Atlantic) and SBC sell asymmetric DSL. They each have a different brand name for their offerings. Infospeed DSL is the name of the Verizon offering; PACbel and SBC simply call their service DSL, and BellSouth offers MegaBit Select and MegaBit Deluxe.

Who buys DSL from incumbent telephone companies?

Currently, mostly residential customers who live close enough to telephone company offices to qualify buy DSL. Most business customers do not purchase DSL from incumbent telephone companies because they want symmetric, not asymmetric, service. Business customers need high-speed service for both sending and receiving files from the Internet.

Who else sells DSL service?

In addition to incumbent telephone companies such as SBC, BellSouth, and US West, DSL is sold by Internet service providers, long-distance companies, and competitive local exchange carriers. Service providers such as Concentric Networks, EarthLink, WorldCom, Cyber Access, Flashcom, ShoreNet, and Verio offer DSL. For the most part, they resell DSL from wholesalers such as NorthPoint, Covad, incumbent telephone companies, and Rhythms.

Some companies such as HarvardNet, Vittsm, and Digital Broadband sell DSL directly to end users without using wholesalers for the DSL modem and telephone company coordination. These service providers also install the DSL modem or modem/router if the end user needs Internet access for multiple computers. The router directs email and Web traffic to the appropriate computer.

In addition to Internet access, all of these providers sell email, security software, and Web page hosting.

What is a wholesaler's role?

Wholesalers such as Covad, Rhythms, and NorthPoint buy copper local loops that run from telephone companies to customers' premises. They also rent space in telephone company central offices, where they place their DSL equipment. Specialized DSL equipment in the telephone company offices aggregate traffic from multiple DSL users and send it in one high-speed stream to the Internet service provider or competitive local exchange carrier.

In addition, the incumbent telephone companies such as Verizon sell their DSL service wholesale to Internet service providers, who resell it to residential consumers.

Wholesalers install the DSL modems at customer premises for service providers that sell directly to end users. See figure 1 for a sample DSL configuration.

Figure 1

A sample DSL configuration.

What type of DSL do most Internet service providers sell?

The DSL service offered by incumbent telephone company competitors is usually symmetric DSL (SDSL). SDSL has the same speed for downloading and sending to the Internet. LAN connectivity is offered to other corporate sites, Internet access, and Web hosting for the customer's Internet domain name, as well as email service. Because the telephone company ADSL service is asymmetric, slower speeds are available for sending to the Internet than when receiving information from the Internet.

Service providers claim that businesses send large files and thus need equal speeds for sending as well as downloading from the Internet. Residential consumers send mainly email messages that do not require high speeds. However, businesspeople tend to send large files such as PowerPoint and Excell attachments in addition to simple text emails.

What is ADSL Lite?

ADSL Lite has asymmetric, lower speeds from the user to the Internet than from the Internet to the user. The "Lite" refers to an ADSL standard that does not require a splitter. (A splitter separates voice signals from data signals on cable that supports voice and data.) Not having a splitter makes ADSL easier to install. Telephone companies hope to install DSL service without dispatching a technician. Telephone companies sell a mix of ADSL and ADSL Lite.

What about home pages for DSL provided by incumbent telephone companies?

If customers have an Internet home page, the address for that home page will be something like www.telcousername.com rather than www.username.com.

How is DSL different from ISDN?

Unlike ISDN, DSL is "always on." No dialing is required, and there are no usage charges. DSL provides faster Internet and LAN downloads.

What are sample ADSL rates and speeds for telephone company DSL?

The following table gives some sample ADSL rates and speeds:

Monthly Cost

Download from the Internet

Upstream to the Internet or LAN

$39.95

640Kbps*

90Kbps

$59.95

1.6Mbps**

90Kbps

$109.95

7.1Mbps

640Kbps

*Thousand bits per second **Million bits per second

What are sample speeds and costs for residential consumers?

Residential fees for ADSL are generally $40 to $50 per month. Speeds are about 90 thousand bits per second from customers' computers to the Internet, and 640 thousand bits per second from the Internet to users' computers. EarthLink and other Internet service providers resell this type of incumbent telephone company asymmetric DSL to residential consumers.

What are sample speeds and costs for business customers?

Speeds range from 144, 160, and 784 thousand bits per second to 1.54 million bits per second. Higher-speed DSL is more costly than lower-speed service, and the number of IP and mailbox addresses and hosting requirements also impacts costs. Monthly service ranges from $150 for the lowest-speed service to $800.

Where is DSL available?

Service is most readily available in large metropolitan areas and their immediate suburbs.

Service is available only at sites less than 2 miles from a telco central office. This includes about 85 percent of customers.

The condition of the outside telephone company cabling impacts availability. DSL does not work on cabling that has bridge taps. (Bridge taps allow multiple customers to share a length of cabling.) According to Verizon, about 20 percent of metropolitan and 60 percent of suburban locations have bridge taps in the Verizon territory. In addition, customers must not be more than a certain number of feet from the nearest telephone company central office. About 85 percent of customers are close enough to central offices to get DSL service.

How are repairs handled?

If a customer has a repair problem, he or she calls the service provider, who determines whether the trouble is in the DSL hardware or the telephone line. If it is in the telephone line, the provider calls the wholesaler, such as Covad or NorthPoint. The wholesaler reports the trouble to the incumbent telephone company, such as SBC.

What equipment is needed for residential DSL service?

A DSL modem and an Ethernet card are required. The service works with both Mac- and Windows-based computers. Some new computers come with DSL Lite modems preinstalled.

Presently most telco-provided DSL service works with only one computer per site. LAN connections at the originating site are not supported. However, a telecommuter with DSL can connect to a remote LAN. In addition, customers can hook up their own routers to access the same DSL line from multiple computers. However, the telephone company will not help customers with the configuration.

Improvements in Availability of DSL

The key enhancement that most customers want is a higher availability of DSL. High-speed Internet access is not obtainable uniformly throughout the United States. Rural areas have the least availability because of the prevalence of long distances between customers and the telephone company central offices. Even in metropolitan and suburban locations, availability is uneven.

New technologies are now available that are capable of extending the reach of DSL. However, they require investments by both incumbent and competitive local exchange carriers.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020