There isn't a specific, universally recognized system made of exactly 25 satellites. To identify a system, we need more information.

Here's why and what questions to ask:

* Purpose: What is the system designed to do? Navigation, communication, Earth observation, scientific research, etc.?

* Orbit: What kind of orbit do the satellites occupy? Low Earth Orbit (LEO), Medium Earth Orbit (MEO), Geostationary Orbit (GEO), etc.?

* Owner/Operator: Is it a government program, a private company, or a collaboration?

Examples:

* GPS: The Global Positioning System has 31 operational satellites, but this number can fluctuate.

* Starlink: SpaceX's internet constellation aims to have thousands of satellites in orbit, but they launch in batches.

* OneWeb: Another internet constellation competitor, OneWeb currently has over 600 satellites in orbit.

To give you a specific answer, please provide more details about the system you're interested in.