Basics
About 56K Modems
There are currently 3 different '56k' protocols in use. The X2 protocol was
developed by US Robotics (now 3com) and was the first to be marketed, although
it is no longer a current protocol. K56Flex was developed by Rockwell and
Lucent and is now also no longer marketed by the modem manufacturers. The
current 56k standard (and the protocol that all major manufacturers are
upgrading to) is the v.90 protocol. While the three protocols are remarkably
different, they all share the same needs in terms of line quality and
negotiation properties.
Requirements
All protocols assume the phone line is part of a modern Public Switched
Telephone Network (PSTN), which most areas now have. The
protocols work by taking advantage of the digital connections that ISPs like
ECPI.com use to connect to the PSTN. Typically, the only analog connection
between your modem and ECPI.com is the one between your home and the phone's
switching office. If there is more than one analog-to-digital conversion in the
loop from your house to the ISP (if the phone company has some extra analog
switch), then neither protocol will achieve the increased performance.
Phone
Lines
The X2, K56Flex, and v.90 protocols depend on high quality phone lines between
your modem and the local phone company's digital switch. Any noise on this
portion of the lines will result in deteriorated performance. This 'noise' is
not necessarily audible sound. All phone lines carry some degree of 'noise'.
Unfortunately,
local telephone companies offer no guarantee of line quality, where data
communications are involved. The 'official' policy, depending on who you talk
to at the phone company, is that they only support something between 2.4K and
9.6K connections. Some of our customers have reported that they have contacted
the local phone company and requested a "data line conditioning kit",
which is something installed at the phone company's switch, and has improved their
connection. Other customers have requested this and been told it doesn't exist.
If
you suspect that line noise might be giving you problems with your connection,
ECPI.com recommends that you do try contacting your local telephone company. If
you hear any audible noise on the phone line, they should take measures to
eliminate that. The phone company seems to also respond better if they get
reports of problems sending faxes.
Checking
Your Lines
ECPI.com recommends that all customers check their phone lines before they
purchase a 56K modem since not all phone lines will support them. To do
so, simply use a 28.8K or 33.6K modem to dial the US Robotics test line with a
standard terminal program (eg. Windows Terminal, Windows 95/98 HyperTerminal,
Macintosh MacComCenter). Follow the instructions at
3Com/US Robotics' web site. Then you should receive a response as to whether or
not your line is 56k capable. Please note that this line test will not work if
done with a 14.4K modem, and will return false 'positives' with a 56K modem.
About
56K Modems and Connect Speeds By FCC regulation, the 56k modems
cannot connect above 53K. A full 56K is theoretically possible, but we have not
been able to verify that any of our customers have reached this speed. Our
experience is that most connections made with 56K modems will be in the range
of 30K to 40K.
If
you use Windows 95/98, Dialup Networking will report either an initial connect
speed or a port speed. Neither of these are particularly meaningful. Both 56K
protocols continually 'renegotiate' the connection, adjusting the current speed
up or down to compensate for line conditions, which do not remain constant. The
new speed is not reported through Win95 Dialup Networking (or most other
operating systems).
Unstable
Connections and Poor Transfer Speeds
Modem manufacturers were very eager to get their new high speed modems on the
market. Both the X2 and the K56Flex modems were initially released in a very
problematic state. Both offered unstable connections and low transfer rates.
Almost all modem manufacturers now have firmware upgrades available for these
early versions to upgrade them to v.90.