In spite of the progress in the communication sphere simple analog modems
remain the most popular and widespread for arranging network connections.
Although they can't ensure a data rate acceptable for all tasks, it's possible
to establish a network access wherever you are (the only condition is that
a telephone line must be at hand). That is why modems are still in great
demand and the situation will hardly change in the nearest 5 years, at
least on our local market in Russia.
Modems can be divided into two groups - internal and external. Internal
ones are installed inside PC cases, while external modems communicate with
PCs via one of external interfaces. A standard serial port is used most
of all though the percentage of modems using a USB bus is rapidly growing.
In both cases modems use a wired connection which makes certain limitations.
First of all, a modem can connect only one computer at a time. If you have
more, you will need to arrange a network (even if you are not going to
access a network simultaneously on several PCs), or to reconnect the modem.
Secondly, it must be located at a certain (usually short) distance from
the PC. A phone cable must be brought to the workplace though it would
be much more convenient to tie such equipment to phone jacks rather than
to computers (if you are going to rearrange or move your workplace you
don't have to bother about the modem). Besides, while a USB cable is thin
enough, COM cables are pretty thick. Thirdly, a modem takes a PC port forever.
Well, if serial ports are not needed for anything else, and COM ports can
be easily sacrificed, soon such ports will disappear at all. And USB ports
are becoming a scarce resource. 
All these problems can be solved with an undirected wireless interface
such as the Bluetooth. In this case a modem can be used by any computer
with a BT adapter located in the vicinity, and it spares you from stretching
a phone cable to the PC (such modem can be located at a distance near a
phone jack), and using a dongle connected to only one USB port you can
connect other equipment as well. Yet a short time ago it was a problem
to find a modem with the Bluetooth interface. But we have recently got
such device and today we will try to find out whether it makes a practical
sense to use it.
First impressions
The package looks like other boxes from X-Micro: carefully designed and
bright. It clearly shows what's inside and it can do. In particular, it
says that this is "Bluetooth 56K Modem" supporting the protocols up to
V.92 and the Bluetooth Class 1.
The modem comes only with a power supply unit, a phone cable and instructions.
No drivers, no software.. it's not needed. Let's better have a look at
the modem itself.
It looks very similar to classical external models. The only thing that
distinguishes it is its antenna. In general it looks pretty.
LEDs that help to monitor the modem are one of the main advantages of external
models. This one has 5 LEDs though only three are typical of an ordinary
modem - CD, TX and RX. PWR indicates power supply, and BT goes on when
data are transferred between the modem and PC.
The backside has no interface connectors, only the antenna. Next to it
is a power supply connector and a power switch; a phone line jack is shifted
to the other edge. Unfortunately, you can't arrange a passthrough connection.
On the other hand, a number of other external modems have it the same way.
Besides, it has become normal that even with two connectors a phone connected
via a modem does not disconnect.
The heart is the Conexant CX06827-11 chip used in many external wired models.
A while ago we tested one
from Creative. There is more than one chip which both modems have in common.
Modem section
I'm not a great expert in this issue, but it's not needed. This chip is
used in many other models, that is why you can get an idea of its operation
from other reviews. I will only focus on its downsides in comparison with
wired solutions. First of all, I have no idea how to change a firmware
version. There are no connectors and drivers. Secondly, I can't change
any settings. The modem is specific due to its interface, and I couldn't
even make it obey the command ATI11. So, the modem is to be used only on
very good automatic telephone exchange. I ran the modem on a local one
and got the impression that it works just a little slower than the popular
Genius GM56PCI-L. It holds the line well but sometimes it goes into a deep
retrain for 10-12 sec where the Genius works at full speed.
No cables!
On one hand, such modem is not entirely free of cables because a phone
cable is needed, in contrast to cell phones with the Bluetooth interface
playing a role of GPRS modem. But far not everyone needs it to be entirely
independent. Sometimes it's enough that it's unnecessary to change phone
wiring. The idea looks similar to wireless phones: the base can be located
in a single place, and a receiver can be used everywhere within a certain
radius.
The modem solves this problem but I think that the compliance to the
Class 1 that ensures operation at the distance up to 100 m is too much.
Just imagine a malicious hacker with a notebook and a dongle of the first
class trying to interfere :)
How does it work if there is no software? It's simple - the only thing
that the modem can do is to enable two services in the BT network: remote
access and fax. Any PC BT adapter is able to use both these services.
These services works even if there are no modems in the coverage area (only
it causes an error). If there are more than one computer, the modem will
be tied up to the first PC that addresses it. At the same time, there is
nothing to connect and install. The only peculiarity is that the modem
doesn't support protected connection, and you must disable protection for
these services in the adapter's settings (it's enabled by default). One
of the leaflets provided warns about it:)
The last step is to select the Bluetooth Fax Modem in the settings
of remote access connection or a fax program. The fact that it uses a wireless
radio channel instead f a USB port doesn't impose more requirements. The
modem can laso be located in any place of your apartment. And it's better
to take a USB port for a dongle which can be used for connection with a
modem, phone, printer and other equipment instead of sacrifying it for
a single modem. The only thing I don't get is why the speed of the port
for a BT modem is limited by 115200 bit/s? The symmetrical protocol allows
for a twice higher speed, and the asymmetrical channels can pump 4 times
as more data. The need in a higher port speed on the V.92 protocol is obvious.
But this is a problem with the dongles software.
Summary
So, we have a good modem for good phone lines. The only its peculiarity
(wireless radio connection with PC) doesn't tell on execution of basic
tasks, and it has both advantages (you can place the modem anywhere in
your apartment near phone jacks instead of rearranging it for tasks), and
disadvantages (difficult to make settings and impossible to change the
firmware version). But I think that this modem will meet the need of many
users.
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