Linux Winmodem Support
Linmodem source code is listed below.
We've got a discussion
, an announcements-only
mailing list, and this web page. I'm working on new archives
which Google will index more happily. They have a copy of the
archives, not the live archives themselves, so currently new
articles aren't being added.
The FIRST step towards finding a Linux driver is identifying
the modem's CHIPSET. The NameFresh.com tool will help
you. Please download and run the scanModem tool before sending any
query to discuss [at] linmodems.org. The chipset will be recognized and
cogent updated knowledge and URLs written out. The manufacturer brand
with model number are generally NOT informative in this
regard. Modems from a single manufacturer can have different
chips. But your documentation may have this critical information, so
read it carefully. Controller based modems utilize the "standard" serial
drivers, while the winmodems in most newer PCs and laptops require
their own drivers.
"Only after your chipset has been identified should help be sought from the
mailing list, discuss [at] linmodems.org, wherein discussions on many issues reside."
Id Software's John Carmack has posited that a linmodem may be able
to have lower latency than a controller-ful modem. This is an issue
of great importance to real-time gamers, as the slightest decrease in
latency translates into a higher score.
Russ Nelson writes: A lot of people claim that a Winmodem has no
place in a Linux box. I disagree. There are many applications for a
Winmodem if you stop thinking of it as a modem, and start thinking of
it as a telephone interface:
- Think telephone emulation (put the audio card into full duplex, and
talk to the linmodem with it).
- Think telephone with a backspace key (use the linmodem to dial for you).
- Think smart telephone: "That line is busy. Do you want me to retry in
- Think "voice dialling".
- Think "soft pbx". Equip
enough machines in an office for all the outside lines. Then do IP
telephone inter-office, and go to a linmodem when you need an outside
- Think answering machine.
- Think pager interface. (Your answering machine takes the call,
phones your pager company and pages you).
- Think "contact database with integral dialler, and answering
- Think "call recording with no off-hook click".
- Think message detail recorder (basically a record of all time
spent on the phone. Great for billing).
None of these require more CPU than a 386.
All winmodems are implemented via a chipset that a modem
manufacturer solders onto a board. For better or worse, they're all
incompatible with each other, just like Ethernet chipsets. Worse
(definitely for worse), some of them seem to have documentation which
is not publicly available. Some chipsets are listed below. Note that
not all chipsets are equal. Some have a DSP. Some do not and hence
require host signal processing (HSP). For the purposes listed above,
a DSP helps very little.
- The late
Tony Fischer also has a generic
modem. He has written a working fax modem software (but only for
a Silicon Graphics Indy). He has also worked on a v.34 modem. He
also has got a circuit dragram (and also PCB design) diagram of an LTU
(Line Terminating Unit). He was writing a book entitled "Soft Modems:
Structured Design and Implementation" at the time of his death.
- The Linux
Reveal VM100 Project looks interesting. The VM100 is
an interface between a phone line and a sound card.
Unfortunately, the VM100 is no longer in production. You
might still be able to find one on EBay.
- The echo canceler (hard part of v.34) seems to be solved.
- For a quality Linux web server, check out Hostgator coupon for coupon codes and deals.
- Intel is supporting a standard for its motherboards
It's on almost every 810 motherboard, and many 820 and
recent VIA motherboards have these AMR slots. AMR means
Audio Modem Riser. Its a special small slot, replacing one
of the PCI or ISA slot positions. It carries analogue
audio from the motherboard's AC97 codec, and some control
lines. The small card which plugs into this slot carries
only the bare line interface circuitry. Being on a
separate card, it is easy to make a variety of versions to
meet each region's local telecom standards. It should be
ideal for simple CTI and modem applications.