There may be several reasons
for this:
First, the highest connection the FCC allows over standard phone
lines is 53.3k. This is the fastest connect rate you can get. If
your are connecting in the 40k-50k range, this is considered good for
most dial up connections.
If you connect at a rate less than you would like, your modems 56k
protocol may not be compatible with ours. We support the fastest and
most common protocols, 56k Flex and V.90. You can attempt to update
your modem drivers.
The biggest factor in determining connection speed are telephone lines.
Age of the telephone lines in your area, "line noise", and weather can
all effect your line quality. If you are concerned about the quality
of your phone lines, please call you local telephone company. However,
keep in mind that the fastest speed the phone companies guarantee is
typically 21k.
Lastly, as the technology of modems has advanced they have become less
forgiving to phone line noise. Often we see a customer with a new PC
and/or modem who suddenly can't connect. This has to do with the fact
that the new high-speed modem protocols don't operate on a poor connection
and will attempt to downgrade the protocol to something that will accept
the conditions. On many new modems the old protocols are not installed
because the manufacturers need to save money and keep the cost of the
modem down and gamble that you won't need the lesser protocol anyway.
So when the switch tries to downgrade the protocol to something that
isn't supported on your modem, you are immediately disconnected. Trying
an older modem from the same location can sometimes demonstrate this
phenomenon and installing an older or more expensive modem with more
installed protocols can solve the problem sometimes too. We suggest
external hardware modems for the best dial-up connection.