modem can be commanded to either answer the call immediately, or after a specified number of rings.

In a leased-line connection, the communication circuit between two modems is always present. Dialing and waiting for rings does not occur in this situation. If these two modems want to establish a data link, one must be designated as the originator and the other as the answerer. You can set this manually or automatically.

Manual Connect

Set the modem to leased-line mode. Type the asynchronous command ATD to the originating modem and ATA to the answering, or press the A/O button on the front panel of the originating modem in, and press the A/O button on the front panel of the answering modem out. Use AT*Mn or set S14b0 to select originate or answer mode.

Auto Handshake

If you want handshaking to occur automatically upon power-up, you have to save the leased-line configuration to the power-on profile. Please remember to set the handshake mode before you save the configuration. Be sure that one modem is set to originate mode and the other to answer mode.

AT-Command

Description

AT*M0

When operating over a leased line, modem will

 

handshake in originate mode. (Default)

AT*M1

When operating over a leased line, modem will

 

handshake in answer mode.

Aborting from Leased-Line Operation

If the leased line has not been connected, pressing the D/V switch on the front panel will drop the line and re-attempt to connect to the leased line.

Leased Line Operation 47

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ZyXEL Communications U-336SA user manual Manual Connect, Auto Handshake, Aborting from Leased-Line Operation, AT*M0, AT*M1

U-336S, U-336SA specifications

ZyXEL Communications, a leading global provider of networking and cybersecurity solutions, has offered a range of products designed to cater to various connectivity needs. Among these, the U-336SA and U-336S modems stand out for their reliability and performance, particularly in the dial-up category during the heyday of internet access.

The U-336SA and U-336S modems are external devices that revolutionized the way users connected to the internet in the late 1990s and early 2000s. Designed for both home users and small businesses, these modems supported 33.6 Kbps data transfer rates, which, at the time, were considered cutting-edge. This capability allowed for reasonably swift internet browsing, email communication, and file downloads compared to earlier modems.

One notable feature of both the U-336SA and U-336S models is their plug-and-play functionality. This ease of use made them accessible to even the less tech-savvy users, allowing quick and straightforward installation. Users could connect the modems to their PCs or laptops via a standard serial interface, minimizing setup time and complexity.

Additionally, both modems were equipped with error correction and data compression technologies. The V.42 and V.42bis protocols enhanced data integrity during transmission, ensuring that users experienced fewer disruptions and greater reliability in their connecting experience. This was particularly vital for tasks like file transfers and large downloads, where data integrity was paramount.

The modems also featured compatibility with various operating systems, including early versions of Windows, which expanded their appeal to a broader audience. The U-336SA was specifically engineered as a standalone device, while the U-336S could often be used with existing computer systems, showcasing versatility in various deployment scenarios.

In terms of design, both modems were compact and lightweight, allowing for easy portability. This made them suitable for users who required connectivity on the go or in different locations.

Ultimately, the ZyXEL U-336SA and U-336S modems represent a significant technological achievement in the history of internet connectivity. Their introduction set the stage for subsequent advancements in modem technology and played a crucial role in the evolution towards broadband and high-speed internet access that we enjoy today. Their legacy endures in the foundational technologies and protocols that continue to drive modern telecommunications.