US Robotics USR5610B User Manual page 35

Macintosh Modems 29
My modem isn't Possible solution:
achieving a 56K
Note: U.S. Robotics 56K modems are capable of receiving downloads at
Internet connection.
up to 56 Kbps and sending at 31.2 Kbps. Actual download speeds you
experience may be lower due to varying line conditions. Maximum
download speeds in U.S. and Canada are limited to 53K, due to
regulatory limits on power output.
Our research has shown that the vast majority of telephone lines in North
America can and do support 56K installation. The V.90 protocol allows
for connection speeds of up to 56K, but line conditions may affect the
actual speeds during a given connection. Due to unusual telephone line
configurations, some users will not be able to take full advantage of V.90
technology at this time. In order to achieve a V.90 connection, the
following must occur:
1. The server you're dialing in to must support and provide a digital V.90
signal. Your ISP can provide you with a list of dial-up connections and
information on what those connections currently support.
2. The telephone line between your ISP and your modem must be
capable of supporting a 56K connection and contain only one
analog-to-digital conversion. The 56K signal from your ISP begins as a
digital signal. Somewhere between the ISP and your modem, there will
be a analog-to-digital signal conversion so that your modem can receive
the data. There must be no more than one analog-to-digital signal
conversion in the path from your ISP to your modem. If more than one
analog-to-digital conversion occurs, your connect speeds will default to
V.34 (33.6). There may also be impairments on the local lines between
your ISP and your modem. These impairments can prevent or limit V.90
connection speeds. All telephone calls are routed differently, so you
should try making your 56K connection several times. One way to test
this is to dial into a long distance location. Long distance lines are often
much clearer than local lines. It is important to note that telephone
companies are constantly upgrading their systems. Lines that do not
support 56K today may support 56K in the near future.
3. Your modem must be connecting to a V.90/56K server. A pair of 56K
modems will not connect to each other at V.90/56K speeds.