www.linmodems.org
Status The FIRST step towards finding a Linux driver is identifying the modem's CHIPSET. 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. General information on these issues is available at the 17 Linmodem-Howto. Much more information or driver kits for particular chipsets can be obtained can be obtained at: * 19 Lucent/Agere modem resources Manufacturer names of Lucent or Xircom may be displayed by the query "lspci -vv". Rationale 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. 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). 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 line. Your answering machine takes the call, phones your pager company and pages you). Chipsets 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 do not and hence require host signal processing (HSP). The driver has been released, but PCTel does not distribute it. You can get a copy from 35 PCCHIPS, who puts one of PCTel's modems on their motherboard. And there's a bunch more information about the 37 PCTel. The unofficial PCTel softmodem-Linux 38 Compatibility Database. There's some interesting 40 third-party information about that modem. IBM also provide a driver for the TP 390X, TP570E, 600X, A2*, T2*, and X20 laptops using 48 ThinkPad LT MiniPCI Modem (Lucent Modems only). Open Source Linmodems * Pavel Machek and Richard have some code to try out with 49 lucent winmodems. It will get the phone on- and off-hook, and can do full-duplex transmission and receiving. Related Software * 51 Multimon encodes and decodes a number of audio signals, including AFSK, and DTMF. It presumes that some other driver is accessing the linmodem to retrieve samples from the phone line. He has recently (early March) made substantial progress -- check it out! He has written a working fax modem software (but only for a Silicon Graphics Indy). 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 VM100 is an interface between a phone line and a sound card. It's on almost every 810 motherboard, and many 820 and recent VIA motherboards have these AMR slots. 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 regions local telecoms approvals standards. It should be ideal for simple CTI and modem applications. Linux winmodem pages * Rob Clark has a HUGE listing of 63 modems and winmodems.
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