dial-up and DSL

You have been using a telephone modem to access the Internet. Its rated download speed is 56 kbps. You switch to a digital subscriber line (DSL), which allows you to receive at 384 kbps. In general, your download speed for web pages is faster than it was with your modem; however, your actual download rates vary from only 128kbps to 256kbps. List likely reasons for your not getting a full 384kbps. Explain fully.