Cheat sheet

CT1 — the group that writes what your phone says

3GPP CT WG1 in under an hour

The shape of it

1 What CT1 is and what it makes

2 How the work moves, and how to follow it

1.3 Who writes the words your phone actually sends
CT1 is a room, not a company. Competitors write one document together in it, and what the room did is public: 105699 CT1 documents are on record ^[1], every one of them readable.
2.3 What the group produces, and what one of its documents looks like
A protocol specification is not a description of a good design. It is the list of exact messages, exact fields and exact reactions — including the reaction to a message that arrives wrong.
4.4 How to look at CT1's work yourself, and what the record does not say
The record answers what happened, to which document, at which meeting, and with which outcome word. It never answers why.

1.4 Who writes the words your phone actually sends
A letter count is not a score. It says how many letters crossed, not whether the two groups agreed, and what any one of them said is not in this record at all.
2.3 What the group produces, and what one of its documents looks like
It is easy to read a document like this as a description of what the network does. It binds both ends. The scope applies it to the UE, the AMF, the SMF and the PCF alike §1, so a phone that ignores it is exactly as wrong as a network that does.
3.4 How something gets into a specification
"Agreed" at CT1 is not "published". The document itself says its contents stay subject to continuing work and may change following formal approval, and that a modified document is re-released with a higher version number §Foreword. The working group agreeing a change is a step, not the end of one.
4.4 How to look at CT1's work yourself, and what the record does not say
A number with no method behind it is the easy mistake here. Every count in this course carries the question that produced it and the day it was asked — the list at the foot of this chapter gives that question, not just the figure.

Every one was counted out of a file on this machine. Hover a row to read the question that produced it.

2.2 What the group produces, and what one of its documents looks like
The present document specifies the non-access stratum (NAS) procedures in the 5G system (5GS) used by the protocols for: mobility management between the user equipment (UE) and the access and mobility management function (AMF) …; and session management between the user equipment (UE) and the session management function (SMF) …
3.1 How something gets into a specification
The contents of the present document are subject to continuing work within the TSG and may change following formal TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an identifying change of release date and an increase in version number … y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections, updates, etc.

3 the course explains, out of 201 the document defines — all of them.

The 12 clauses of TS 24.501 this course is built from.

The 20 named sources it cites, by what they are.

Page on the standards body's own site 5

Official 4

Meeting document 3

Specification 3

Meeting 2

Report 2

Working group 1

The same subject, overview — Enough to follow the conversation and know what to look up.
The same subject, in depth — The working reference: every mechanism, every parameter.
Every question of this course — 16 of them, on one page.
The final test — 10 questions, 60 per cent to pass.
The whole of TS 24.501 — all 1340 clauses.
Every source behind the course — 354 of them, each with its method.

105699 CT1 documents on record — rows in the pygppe document database, table tdoc where meeting starts with 'C1-', read 2026-08-04