3Com 3CP5610A User Manual page 23

External Serial Modems 17
My modem isn't Possible solution:
achieving a 56K
Our research has shown that the vast majority of telephone lines in North
Internet connection.
America can and do support V.90/V.92 connections. The V.90/V.92
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/V.92 technology at this time. In order to achieve a
V.90/V.92 connection:
1. The server you're dialing into must support and provide a digital
V.90/V.92 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 an 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 Kbps). There may also be impairments on the local lines
between your ISP and your modem. These impairments can prevent or
limit 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. For a V.90 connection, 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.