covers Secondary Protectors . These are devices designed to protect telephone equipment, data lines, and communication circuits from overvoltages and overcurrents. They are typically installed inside a building (on the "side" of the network interface) and work in conjunction with primary protectors located at the building entrance.

: UL sometimes offers a "Digital View" option on their official portal, allowing users to read standards online for free with a registered account, though printing and downloading are restricted.

: Previous versions limited second-stage regulators to a 10 psig maximum inlet pressure. Revisions now allow for higher inlet pressures to support more efficient community distribution systems. Accessing UL 144: "Free" vs. Official Options

Disclaimer: Standards are updated frequently. The current standard is likely UL 144 5th Edition (or newer). Always consult the latest official document for compliance and design purposes.