TS 23.501 · version 20.2.0 · 1180 clauses · Quick start · 20 minutes
The 5G system architecture
A 5G core network is a set of software functions that call each other, and TS 23.501 is the document that names every one of them and says what it owns. This quick start walks the whole shape of it in four chapters: why such a document has to exist, what the pieces are called, what happens when a phone switches on, and what the network promises about the traffic it carries. It is not a trailer for a longer course — it is the whole subject at the altitude somebody needs on their first day. Every claim links to the clause it came from, so the original text is always one click away.
This course was written against TS 23.501 version 20.2.0, verified 2026-08-04.
The document, all of it
One block per clause of TS 23.501, in the order they appear, sized by how much text the clause holds. Lit blocks are taught in this course.
The chapters
Part 1 What it is and who wrote it
- 1 What this document is, and why it had to be written Why a mobile network needs a written architecture, what TS 23.501 settles, what it deliberately leaves to other documents, and who keeps it. 4 min
- 2 The pieces a 5G core is made of What a network function is, the three that carry a connection, the ones standing behind them, and how the whole set talks. 4 min
Part 2 What it does for a device
- 3 What happens when a phone switches on Registration, the two states the network tracks a device in, and the session it has to ask for before a single packet can leave. 4 min
- 4 What the network promises, and how one network becomes many How traffic inside a session is split into flows with their own promises, how one network is cut into named slices, and where to read on. 5 min
What this course is built on
- Chapters
- 4
- Words written for you
- 3,352
- Clauses covered
- 24 of 1180
- Figures from the document
- 164
- Abbreviations
- 221
- Published versions
- 50