FreeBSD Stable Release 6.0 Installer  Guide



Products offered by the public telephone company


Analog voice dial up service to your ISP

This is what everybody commonly calls voice modem dial in service.


Analog voice ISDN service

This has been around since the 1960's and used to be the only way to get speeds faster than analog voice dial in speeds. It's basically a leased line dedicated to computer usage. This Guide does not contain instructions on configuring legacy ISDN access to the public Internet.


Digital DSL service

DSL, or Digital Subscriber Loop, is a high-speed Internet access technology that uses the standard copper telephone lines. DSL provides a direct, dedicated connection to an ISP via the existing telephone company network. DSL is designed to run on up to 80% of the telephone lines available in the United States. By using line-adaptive modulation, DSL is capable of providing data speeds of 8 Mbps or more.

DSL services are now being aggressively marketed for home and small business use around the USA. DSL is typically priced below ISDN, and well below T1 service, yet can provide potentially even greater speeds than T1 without the cost, complexity, and availability issues of T1. Since DSL is a dedicated line, it provides "always on" service and avoids the delays and use charges that are common with ISDN, making this quite a nice technology for the bandwidth starved Internet power users. This "always on" service has security implications; the user must make provisions for installing a firewall to keep out unwanted intruders.

While all this sounds exciting, DSL does have some drawbacks. The quality of the DSL signal, and thus the connection, depends on distance (the length of the copper "loop") and various other factors. DSL service is basically limited to a 3 mile radius around the phone company's local substations. Also there is no such thing as standard "DSL". There are various flavors of DSL, and many, many ways DSL providers are implementing their networks.

There are PCI DSL internal modems available on the market. Some DSL providers will let you chose what kind on DSL modem to use. Do not select a USB DSL modem. If the external DSL modem has both USB and Ethernet ports, allways use the Ethernet port. Ethernet is a more reliable connection. The DSL modem uses a short Ethernet cable with UTP-45 connector plugs on each end to plug into the DSL modem and the NIC in your FBSD system. For more in-depth description on DSL see


Digital leased lines

These are referred to by the industry as T1 lines and have such a large capacity that home users or small businesses could never fully utilize one. This type of line is very costly. This Guide does not contain instructions on configuring T1 access to the public Internet.


Enabling Voice Phone Modems

If you are following the 'incremental install method' recommended in this Installer Guide, then it's now time to install your voice phone modem. Halt your system and power off the PC. While the power is off, you can cable your external serial modem to the PC com1 nipple or com2 nipple located on the back side of your PC. Or plug your internal PCI modem into any PCI slot.

Installer Note: All instructions are based on 56K type modems. If you are using a legacy modem (9600, 14.4, or 33.6 max baud) it’s your responsibility to adjust the 115200 value to one that is applicable to your modem.


PCI Modem Types

Internal PCI phone modems are manufactured for two target markets, MS/Windows (Winmodems) and every thing else. Winmodems are cheep because the hardware controller function is handled by the software you have to install into MS/Windows. This hardware controller function is normally contained in a chip on the modem circuit board. Winmodems are missing this chip and directs the modem to use driver software running in the MS/Windows system to perform the controller function. The most common Winmodem chips are manufactured by Lucent. There are many versions of this Lucent chip resulting in each chip version needing a different MS/Windows software driver version.

Up until version 4.4, FBSD did not have any solution to using Winmodems, but with the release of 4.4 the ports collection now contains the "Linux Winmodem 'ltmdm' driver" which was ported to FBSD. This port is very poorly documented, only works with a limited number of Lucent chip version, and can be somewhat unreliable. Your whole Internet connection is managed by your modem and trying to shoe horn a modem specially manufactured for the MS/Windows operating system into FBSD is not the way to achieve a satisfactory dialup Internet connection. This guide does not cover installing the ‘ltmdm’ Lucent Winmodem driver port.

Internal ISA expansion slot modem sales has now dropped off to the point where you can no longer buy a new one. Motherboard manufactures have removed the ISA expansion slots from their motherboards. The ISA internal modems have been replaced with internal PCI modems.

The newest entry into the modem market is the USB external modem. FBSD supports USB plug in external modem devices. These are also Winmodem versions of external USB modems, so be careful what you plug into FBSD.

For the FBSD newbie, or for that matter, any FBSD user who wants dial up Internet connection with the least amount of effort, should use an external serial modem for connecting their FBSD box to the Internet. This method works using the default generic kernel, creates no IRQ conflicts with the motherboard BIOS, and will work right out of the box so to say. All external serial modems use the PC's serial port controller built into the motherboard. This has been the standard since PC's first came out. I recommend the Zoom model 3049L external modem; it works right out of the box.

If you want to use an internal PCI modem in FBSD, you have to get a PCI modem card that has an onboard controller and DSP. Even under MS/Windows it's better to use a internal PCI modem that has a hardware controller. These cost around $70.00 to $100.00 in the USA. I recommend the Zoom model 2920 internal PCI PLUS modem.


How to determine if FBSD found my modem at boot time

The boot log /var/run/dmesg.boot is where you look to find out if FBSD found your modem.


External serial modems

If you are using a external serial modem, the PC's BIOS must have the com ports enabled.

This is what you will see in dmesg.boot if your PC BIOS has the com ports enabled.

sio0 at port 0x3f8-0x3ff irq 4 flags 0x10 on isa0
sio0: type 16550A
sio1 at port 0x2f8-0x2ff irq 3 on isa0
sio1: type 16550A

This is what you will see if your PC BIOS has the com ports disabled.

sio0: configured irq 4 not in bitmap of probed irqs 0
sio0 at port 0x3f8-0x3ff irq 4 flags 0x10 on isa0
sio0: type 8250
sio1: configured irq 3 not in bitmap of probed irqs 0

sio0 = PC com1 nipple = FBSD device cuaa0 
sio1 = PC com2 nipple = FBSD device cuaa1

The device name cuaa0 or cuaa1 is the device name you tell 'user ppp' to use to connect to your external modem.


Determining if your external serial modem is

connected to FBSD

FBSD has a program called 'tip'. This program talks directly to the physical PC com ports and to the logical serial com ports, commonly referred to as com1, com2, and com3, and com4. External modems use com1 and com2 because there are only two com port nipples on the back of the PC.

You are going to use the 'tip' command to test if FBSD can communicate with your modem. This test will verify that FBSD can connect to the external serial modem and also that it will respond to the Hayes commands you will issue to it.

The ‘tip comx’ command uses the /etc/remote file for the definition of comx. I have listed the whole group of comx statements here so you can better find them in the /etc/remote file.

ee /etc/remote

# Finger friendly shortcuts


As you can see this file has not been updated to reflect the serial port baud rate of the modern modems currently on the market. These statements are configured for 9600 baud legacy modems which have not been manufactured in 10 years. The serial port baud rate is the speed that the serial port controller talks to the modem hardware. It’s not the speed the modem connects to the remote modem.

Change all the 9600 to 115200 which is the serial port baud rate for 56K modems.

ee /etc/remote    # and make it look like this     

# Finger friendly shortcuts

After saving your changes you are now ready to test your modem.

On the command line enter;

tip comX      where X is the com port your external modem is on.

The available choices are com1 or com2.


is displayed meaning 'tip' has made contact with the external modem.

Type AT and then hit enter.  # 'AT' is the Hayes attention command.

'OK' is displayed.

This means the Hayes attention command was received by the modem and issued its normal reply of 'OK'. Your modem configuration has passed the test and is functional.

You now have to ‘train’ the modem to use 115200 as the internal default baud speed. Enter the ‘AT’ Hayes command 10 times, you will receive the ‘OK’ reply from the modem each time. This is a very important step that has a very large impact on the performance of your modems throughput, do not bypass this step.

Use the keyboard ~ key followed by the . key to exit tip.


This FreeBSD Installer Guide is an public domain HOW-TO.  This content may be reproduced, in any form or by any means, and used by all without permission in writing from the author.