There are many companies that are in great need of an internet connection. Companies with this need have surely looked into a T1 connection, and might even have one, but there are others that might be interested in a T3 connection instead.  Quality goes up with the use of a T3 circuit. This means that the internet connection is fast and the T3 cost is not even that much more extensive than a t1 connection.  With a T3 connection, what you are really doing is just moving the channel bank to your premise and advantageously, there is no loss.

As you go out from the central office, the call loses some amplitude and you get some noise from crosstalk, but when you have it digitally at your facility, the analog piece is only a couple feet long.   In addition, performance and reliability inherent in T3s to date have made them preferential to integrated offers using voice over DSL and voice over IP, which is commonly known as VOIP. However, the challenge is that DSL is not as stable as a plain T3.

Keep in mind that it is common for companies that experience lower change per month in SMB voice lines to see that figure reduced to less with integrated access. The nice thing about T3s is that people do not leave the carrier.

 In addition, it gives the competitor a chance to beat the RBOC at its own game, by allowing the new entrant to lock in local, long-distance and voice revenue over a single integrated product, while saving both its customer and itself a great deal of money. 

Also, if your Internet connectivity goes down, you are inconvenienced. If your phones go down, you are screwed.  In addition, VoIP is gaining some ground among DSL and cable modem users in the small office.

Keep in mind that some companies are offering integrated voice and data services over their proprietary networks through cable, Bell and ISP resellers as well as VARs, system integrators and agent partner sales organizations.

Packet-based IADs are necessary for delivering the enhanced services required to drive revenue streams. Still, service providers are primarily using TDM-based IADs.

DSL was developed at first as an experiment to see how many usable desktop applications can fit inside a 50MB live CD and DSL grew into a project with hundreds of development hours put into refinements including a fully automated remote and local application installation system and a very versatile backup and restore system which may be used with any writable media including a hard drive, a floppy drive, or a USB device. DSL has a nearly complete desktop, and many command line tools.  It is useful when you have a T3 connection to understand the basics of DSL.