4 Where to read it yourself, and what the record cannot say

4.1 Why this chapter exists

Every fact in the three chapters before this one carries a citation, and a citation is only worth something if somebody can open it. So this chapter is the reading list — and, just as usefully, the list of questions the reading will not answer.

4.2 The four documents to open first

TS 23.228 is the stage 2: how the system is put together, and the document everything else refers back to. TS 23.228

TS 24.229 is the stage 3: the call control protocol based on SIP and the associated SDP. No document in this register attracts more IMS change requests, as Who writes it, and what the paperwork looks like counts. TS 24.229

TS 22.228 is the stage 1: what IMS owes users and operators. TS 22.228

TS 22.173 is the telephone service itself — multimedia telephony and its supplementary services. TS 22.173

That sentence is copied as the document writes it, missing verb ending and all.

4.3 The four papers being decided now

Release 20 work can be followed through the paper that opened each piece of it.

• CP-261069, "Study on IMS resiliency", from CT4 at the CT plenary CP-112. CP-261069

• SP-260686, "Revised SID: Study on IMS Architecture Enhancement (FS_enIMS_ARC)", from SA2 at the SA plenary SP-112. SP-260686

• SP-250878, "New WID on AI/ML for IMS services", from SA4 at SP-108. SP-250878

• CP-260044, "IMS Stage-3 IETF Protocol Alignment", from CT1 at CP-111. CP-260044

Each of the four carries the word approved in the store. That word is about the paper and about nothing else: this record has no field anywhere that says whether the work behind a paper is running, stalled or done.

4.4 How big the subject is, in three numbers

345 rows of the 3GPP work plan are IMS work. ^[2] They carry 177 different short names between them. ^[3] Between them they touch 241 specifications. ^[4]

4.5 What this record cannot say

• No date for any release. All 16 release names are held, with version numbers and meeting days beside them; the day a release froze is not. ^[5]

• No publication day for a version. What is stored beside a version is the day its file went up on the 3GPP server — TS 23.228 at 20.0.0 went up on 2026-06-22 — and that is a different day from the day it came out. TS 23.228

• No vote and no objection. 3GPP works by consensus, and no store here holds a tally of who was for or against anything. CP-261069

• No reason for any decision. A paper carries an outcome word and never why the room settled on it. CP-260044

• No status for a piece of work. Nothing says whether a work item is running, stopped or finished; the work plan keeps a completion percentage by hand, and a document's outcome word is about that document alone. FS_enIMS_ARC

• No IMS document before 2015-01-23. ^[6] The work starts at Release 5, and this store's labelling starts on that day, so every count in Who writes it, and what the paperwork looks like is a floor.

4.6 The same subject, twice more

IMS is written three times at this school, from the same register, at three altitudes. The overview course is for somebody who has to follow a conversation about IMS. The in-depth course is for somebody who has to work with it.

This school carries the text of none of the documents named above. What it gives you is the number, what the document says it is for, and a link to 3gpp.org, where the reading is yours.