In-Depth 01: Connecting at Speeds Lower Than The Advertised Speed of the Modem
A common question that CoreComm users have is why their modem doesn't connect at the speed that it is
advertised as. When you buy a 28.8, 33.6 or 56k modem, you expect it to connect at 28.8, 33.6 or 56k, right?
Unfortunately, that's rarely the case. While your 28.8, 33.6 or 56k modem may be capable of those rates as a
maximum connection speed, modem users will typically find that their high speed modem will connect at a speed
lower than the advertised rate (to varying degrees on any online service).
Why is this? The answer has to do almost entirely with phone line conditions. Modems communicate with each other
by making a variety of tones on a variety of frequencies through a voice telephone connection. If there is noise on
the line (such as static, crackle or crosstalk), the modem's tones will be masked by those noises. Other times, a
phone connection may be too weak or too hot, meaning that the tones that the modem makes are either too quiet or too
loud to be interpreted by the other modem. In other cases, a phone connection will be able to transmit some of the
various tone frequencies that the modem makes, but not others, creating a limit to how broad a spectrum of frequencies
the modem can use to communicate with another modem, thereby limiting the speed of the connection. Because of the wide
variance in phone line quality, modem manufacturers do not guarantee that their modems will connect at the highest
speed the modem is capable of.
So who's to blame for the variations in line conditions? Decreases in line quality can occur at three different
points in your connection. The first, known as your local loop, is the copper connection between your modem and the
switch at your phone company's central office. If this loop goes over an especially long distance, and/or if portions
of this connection are linked with older, poor quality copper wire, line conditions can be degraded. The second link
between you and CoreComm is known as the trunk, where your call is carried from your phone company switch
to the switch that CoreComm is connected to. This portion of the connection, unlike your local loop or
CoreComm's loop, does not stay the same. Any time you make a call, even if you are calling the same
number repeatedly, your call can be carried over different trunk lines or through different switches. Because you
may be carried over different lines each time you call, and the quality of trunk lines can vary widely, you may see
a different connection speed each time you call us.
It's also not uncommon that individuals will typically see better connection speeds to some phone numbers than others,
given the fact that calls to different locations are carried over different trunk lines.
The final stage of your connection is the loop between the phone company's switch and CoreComm. To
assure our customers the highest quality connections, we don't use normal analog phone lines. We use what are
called channelized T1 connections at nearly all of our locations. While they transmit sound, similar to a standard
phone line, the channelized T1 connection is a digital connection. This kind of connection is rarely susceptible to
the noise or signal loss problems that are common on other connections, and the bandwidth available for the various
frequencies a modem will use to broadcast information is maximized. In addition to providing a noise-free connection
to all users, the digital quality of the channelized T1 connection from CoreComm to the phone company is
what allows customers to connect at higher speeds with 56k modems.
The most common source of low line quality is in the loop between the customer and their phone company. This can be
due to poor wiring within one's business or residence, the distance between the customer and their telephone company,
or due to interference on the line. If this is the case, there are a few things you can do:
- Try a different brand, make and/or model of modem. Different modems have different abilities at handling
adverse line conditions. Typically, the more inexpensive modems will be more prone to disconnections or low
connection speeds. The 3Com/USRobotics Courier line of modems are known for their superior line handling
abilities. Those who are getting poor connections with more inexpensive modems will often find connections
acceptable with the Courier.
- Contact the phone company's repair department, and ask them to do a free line test. If they detect a problem
on the portion of the line from your telco interface box to their central office, they will repair the line free
of charge. Unfortunately, however, most phone companies will only guarantee their standard phone lines to 9600
baud -- the phone company may tell you your line is 'clean', even though it's only capable of reliable connections
of up to 9,600 baud. Some phone companies are starting to guarantee connections at 14,400. Call your telephone
service provider to ask what they guarantee for you.
- Test the wiring in your home. If you're handy, you can replace the wire from the phone company's interface
box to your modem with fresh cable.
- If there are adverse weather conditions, including damp ground, phone line conditions will be negatively
affected. Each spring, we see an increase in the number of complaints about low line speeds because the
quality of phone lines can be affected by damp weather and/or electrical storms.
- If you live in a rural area, or have recently purchased a second phone line, the phone company may have
multiplexed your line. Multiplexing is the practice of using a single physical phone line to carry calls to
multiple phone numbers. If you previously had one phone number and order a second, the phone company may
simply "divide" that line into two: resulting in a slower connection on one or more of the lines going into
your house. If you were previously able to connect at high speeds when you had a single line, but got a
second line and found your connection speed dropped considerably, call the phone company to see if they can
connect two physical lines to your location instead of splitting a single line into two. In rural areas, it
is common to split a single line between multiple residences: the same suggestion applies.
The least likely source of connection problems is the loop between the phone company and CoreComm.
Our digital channelized T1 lines, superior to normal lines, are virtually error-free -- and if errors do occur, we're
notified of them, and can resolve problems with those lines immediately. With digital lines and the highest quality
modems on our end, you can be assured that we are using the best possible equipment at CoreComm to allow
you to get a high speed connection.
So, what if you've done everything above to make sure the problem isn't with your local loop to the phone company
or your modem, and are still getting low connect rates...and/or find that you can connect with other providers at
higher speeds than you can with CoreComm? Unfortunately, this indicates that there are problems with
the way that the phone company is routing the call from your location to ours through the "trunk" lines. Similarly,
some users have found that their connection speeds can vary based on time of day -- this can be attributed as well
to the way the phone company trunks your call during periods when a large number of lines in your area, or on a
particular trunk, are in use. In some cases, users will find they'll actually be able to connect faster with a
one of our dial-up lines that is long distance to them rather than their local dial-up. This is due to differences
in the trunks and switching equipment used by the phone company when connecting long distance connections as opposed
to local connection. Regrettably, there's little that you or CoreComm can do about cases of this sort.
This is caused by the limitations of the way your local phone company is routing your call. If you find any of
these situations to be the case for you, and you wish to remain with CoreComm, you may want to consider
an ISDN line, which is a digital line that your local phone company will guarantee a 128kbps connection between you
and CoreComm. More information on ISDN can be found in our
ISDN FAQ.
Ironically, without an ISDN line, you won't ever find yourself connecting at a true 56k speed with a v.90 modem.
While all v.90 modems are capable of connecting at 56k speeds, FCC regulations on the national phone companies prevent
connections at speeds over 53.3kbps on analog lines. Even 53.3kbps speeds, however, aren't very common at this time.
Most 56k modem users see connection speeds between 35kbps and 50kbps, with 44 and 46kbps speeds being the most common.
The reason for this is the same as for why you may get lower than maximum connection speeds with 28.8 and 33.6 modems
-- variation in line quality.
While most 56k modem owners are capable of getting v.90 speeds (above 33.6) when connecting with our 56k-compatible
lines, some aren't able to get speeds more than which are typical for 28.8 or 33.6 modems. As mentioned above,
CoreComm has digital lines, which allow us an error free connection to the phone company. When you
call into CoreComm on a standard phone line, your connection must somewhere along the way be converted
by the phone company to a digital signal. 56K connections require that the line you're calling in on has no more than
one analog to digital conversion. If additional conversions from analog to digital (or vice versa) are made, the modem
will not be able to connect at speeds beyond a normal 28.8 or 33.6 modem. This configuration is determined by your
phone company, and cannot be altered by yourself or by CoreComm.
Some users have found that they are able to connect at 56k speeds during some times of the day and not others.
This is attributable to changes in the way the phone company trunks your call during periods when a large number
of lines in your area, or on a particular trunk, are in use.
3Com has a line test utility to see if your local loop is compatible with 56k modems. You can get information on
how to take the linetest at the 3Com web site.
We at CoreComm do wish to stress that through our investments in digital line technology and high
quality modems, we have made certain that we are providing you the ability to connect at the highest speeds possible
with your particular phone line. We want to see every customer get the fastest connection they can. Unfortunately,
as listed above, there are times where elements outside of CoreComm's control keep our customers from
getting a connection at the highest speed their modem is capable of.
If you have additional questions about modem connections, here are some excellent resources for learning more about
the way your modem works:
