User Tools

Site Tools


Getting Ready for SDF Dialup - Equipment

Typical requirements for dial-up networking:

  • an SDF DIALUP account (username, password, and access numbers)
  • a computer that supports PPP dial-up networking
  • a POTS (Plain Old Telephone Service) line (aka a “land line”)
  • a two-wire phone cord with RJ-11 connectors
  • an analog modem (aka “56k modem” or “dial-up modem”)

Assuming you've got the first two items taken care of…

Getting a POTS line

You'll need to contact your local telco company for this; in the US this will usually be either one of the “baby Bells” like Qwest, or Verizon. Check your local telephone directory if you're unsure. Typical cost for a basic land line is around $25/month with all the taxes. About the only extra you might want is call waiting if your modem is V.92 (see below) and you don't want to miss incoming calls. Don't be surprised if the telco asks for a deposit and takes a week to activate your line…

Phone Cords

These can be picked up almost anywhere; chances are you already have one. That said, the typical flat phone cord isn't ideal as there is barely enough copper to carry a signal and the pair isn't twisted. Best option is to get some connector crimps and modern communication cable and make your own cord. And don't stop at the phone jack; if the wires running to the customer service box are really old replace them too.

Dialup Modems

“Modem” stands for MOdulator-DEModulator and is a device that modulates/demodulates an analog carrier signal to encode/decode digital information. Modems allow digital computers to communicate over analog telephone lines. In the case of dial-up, the modem is of “narrow band”, ie. it operates within the traditional POTS frequency band of 0 to 4 KHz.

Physical Types: In vs Out

There's basically two types:

  • Internal:
    • typically a bus-powered card installed inside a PC; sometimes integrated into the main system board.
    • Examples are: ISA (obsolete), PCI (current), PCMCIA (obsolete), mini-PCI (current).
  • External:
    • stand-alone units, typically with multiple indicator lights and external power supply.
    • Most have legacy DB9 or DB25 serial ports and use standard serial cables to connect to the PC, though USB-based units are also available.
    • Various PCI/PCIe cards and USB adapters are available to add serial support to newer computers.

Functional Types: Soft vs Hard

Modems can either be HARDware or SOFTware driven. Software modems (softmodems) require OS-specific drivers to function whereas hardware modems (hardmodems) rely on self-contained controller chips for functionality and are therefor generally OS-independent.

In general:

  • most internal modems are softmodems (aka “WinModems”) and often only work with Microsoft Windows OS
  • most external modems are hardmodems, though some USB modems are driver-dependent (ie. softmodems)

Users in need of a hardmodem should look for terms like “controller-based” or “supports DOS/Linux/Mac OSX”

Current Modem Protocols and Speeds:

Modern telco networks switched to digital equipment in the late 1990s; the V.90/V.92 modem protocols were designed to take advantage of those telco upgrades and make use of hardware compression to increase transmission rates up to 320.0 kbits/s.

  • V.90: cir. 1999; 53.3 kbit/s download and 33.6 kbit/s upload
  • V.92: cir. 2000; 53.3 kbit/s download and 53.3 kbit/s upload ; supports call-waiting

Most SDF Dialup access numbers support at least V.90. Older modems may work as well but at slower speeds - ie. V.34 modems operate at 28.8 kbits/s

General Setup

Internal modems are easy: just install it in an open card bay, plug one end of the phone cord into the the modem jack, the other into the phone jack in the wall/baseboard. External modems work similarly except you'll also need to connect the modem to the computer via either a serial or USB cable, and of course plug in the modem's power supply. Once all the cables are connected, power up and configure the dial-up PPP network connection (see the Windows and Ubuntu examples).


$Id: dialup_equipment.html,v 1.2 2011/01/16 09:43:09 jgw Exp $ Getting Ready for SDF Dialup: Equipment - traditional link (using RCS)

getting_ready_for_sdf_dialup_-_equipment.txt · Last modified: 2021/04/01 04:44 by hc9