How Windows 98 Handled Dial-Up Networking

In Microsoft Windows 98, Dial-Up Networking (DUN) was the primary gateway to the internet, integrating modem hardware controls, telecommunication protocols, and automated setup wizards directly into the operating system. Built upon the Telephony Application Programming Interface (TAPI) and the Point-to-Point Protocol (PPP), Windows 98 streamlined the process of turning an analog telephone line into a functional TCP/IP connection. This article explores the architecture, connection sequence, and features that defined the dial-up experience in Windows 98.

The Dial-Up Networking Architecture

Windows 98 handled remote connections through a dedicated system folder located in "My Computer" named Dial-Up Networking. This subsystem acted as a network adapter emulator, allowing remote servers to appear to the OS as local network nodes.

At the hardware level, Windows 98 relied on the Unimodem V driver architecture and TAPI 2.1. When a user installed an internal PCI modem or external serial modem, Plug and Play detected the device and assigned it an IRQ (Interrupt Request) and a COM port. TAPI managed dialing rules, handling area codes, call waiting disable codes (such as *70), and pulse or tone dialing.

Establishing a Connection

To get online, users configured connections via the "Make New Connection" wizard. The operating system handled the connection process through several distinct stages:

  1. Initialization: The system sent standard Hayes "AT" commands to the modem to reset the hardware and prepare it for dialing.
  2. Dialing and Handshake: The modem took the phone line off the hook and dialed the Internet Service Provider’s (ISP) access number. Windows 98 piped the audio through the modem's internal speaker, allowing users to hear the high-pitched negotiation tones as the modem negotiated protocols (such as V.90 for 56 kbps speeds).
  3. Authentication: Once a carrier signal was locked, the OS initiated the Point-to-Point Protocol (PPP). Windows 98 supported Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP) to securely transmit the user's credentials to the remote access server.
  4. Network Layer Configuration: After authentication, the Internet Protocol Control Protocol (IPCP) negotiated connection details. In most setups, the ISP dynamically assigned an IP address, subnet mask, and DNS server addresses directly to Windows 98's native TCP/IP stack.

Advanced Features in Windows 98

Windows 98 included several enhancements over Windows 95 to improve connection reliability and flexibility:

  • Dial-Up Scripting: For non-standard ISPs requiring interactive terminal logins, Windows 98 included native scripting support (.scp files) to automate command-line login sequences.
  • Multilink Channel Aggregation: Windows 98 supported Multilink PPP (MLPPP), enabling users to combine two separate analog modems and phone lines—or dual ISDN channels—into a single logical connection, effectively doubling bandwidth.
  • Internet Connection Sharing (ICS): Introduced with Windows 98 Second Edition (SE), ICS allowed the computer handling the dial-up connection to function as a Network Address Translation (NAT) router and DHCP server. This enabled other computers on a local Ethernet network to share a single dial-up internet connection simultaneously.