School of Specs IMS — the call as an internet sessionQuick start

Who builds it, and where to read it · chapter 3 of 4 · 4 minutes

3 Who writes it, and what the paperwork looks like

The groups that share IMS between them, how much each has filed, and why most of the pile is change requests to documents that already exist.

3.1 No group owns IMS

None of the groups in this register is an IMS group. The subject is cut across fourteen of them, and each owns a rung or a corner rather than the subject. 309 separate meetings have had an IMS document on the table. [2]

Six of them are the ones this course keeps returning to. They are not simply the six largest: RAN5, which does the conformance testing, has 147 IMS documents, more than SA1's 88. RAN5

Group What it does here Documents Meetings
CT1 mobility, call control, session management 2169 66
CT4 core network protocols 746 48
CT3 interworking with other networks 719 47
SA2 architecture 429 30
SA4 codecs and media 186 27
SA1 services and requirements 88 7

The three documents What IMS is: a call carried as an internet session opens with all have an owner in that list. TS 24.229, the protocol, is CT1's. TS 24.229 TS 23.228, how the system is put together, is SA2's. TS 23.228 TS 22.228, the requirements, is SA1's. TS 22.228

3.2 Where the deciding happens

The working groups write the text; the plenaries above them take the papers. The CT plenary has 221 IMS documents on record CT, the SA plenary 34 SA and the RAN plenary 25 RAN.

The plenaries carry the decisions and not the drafting, which is why their counts are small beside CT1's.

The single busiest meeting in this register is CT1#112, held in West Palm Beach, Florida from 2018-08-20 to 2018-08-24, with 206 IMS documents on the table. [3] C1-112

3.3 What arrives, and in what shape

4939 IMS meeting documents are on record. [4] 3509 of them are change requests. [5]

A change request is the only way a published specification is ever altered. A pile made mostly of them is a subject being maintained rather than one still being invented.

Another 767 are pCRs, the proposed text of a study report — homework rather than rule-writing. [6]

1680 of those 4939 documents name TS 24.229 as the document they change, more than any other document in this register. [7]

The work that never stops is the one that keeps that protocol aligned with the IETF, IMSProtoc20-CT in its Release 20 phase, and it still opens where the subject began. IMSProtoc20-CT

The Release 8 phase of the same work opened with those two sentences too, one verb apart. [8]

3.4 Who writes them

374 different names appear as the writer of an IMS document. [9] Ericsson wrote 602 of them, more than any other single name in this register. [10]

3.5 Every number above is a floor

The earliest IMS document in this store went up on 2015-01-23. [12] IMS work starts at Release 5, which is where Where it came from, and why it keeps being rebuilt begins, so the store's labelling starts long after the work did.

That makes each count in this chapter a floor and never a total. None of them says anything at all about the years before 2015-01-23, and none of them should be read as "how much work IMS has taken".

3.6 Where this leads

Where to read it yourself, and what the record cannot say names the documents to open first, the four papers being decided in Release 20 right now, and the questions this record cannot answer however long anybody stares at it.

Where the numbers in this chapter come from

  1. why IMSProtoc20-CT was proposed the opening sentences of the justification of the work item description /var/www/whatthespec.net/data/data/wis/1110010/CP-260044/CP-260044.md, copied word for word, read 2026-08-05. That file was taken as this work item's own because it states the unique identifier of this work plan row
  2. 309 meetings have had IMS documents on the table distinct meeting codes over the IMS documents that are written as a meeting code; a handful of stored codes are a whole ad-hoc title that ran into the field and are counted as documents but not as meetings, asked of /var/www/whatthespec.net/data/database/api/api.sqlite on 2026-08-05
  3. C1-112 handled 206 IMS documents, more than any other single meeting IMS documents grouped by meeting code, largest first, asked of /var/www/whatthespec.net/data/database/api/api.sqlite on 2026-08-05
  4. 4939 IMS meeting documents rows of table `tdoc` whose work item column holds, as a whole word, one of the 177 IMS acronyms — 159 different spellings of that column match, because it sometimes carries two work item names at once, asked of /var/www/whatthespec.net/data/database/api/api.sqlite on 2026-08-05
  5. 3509 IMS documents are of type CR IMS documents whose type column is exactly 'CR', asked of /var/www/whatthespec.net/data/database/api/api.sqlite on 2026-08-05
  6. 767 IMS documents are of type pCR IMS documents whose type column is exactly 'pCR', asked of /var/www/whatthespec.net/data/database/api/api.sqlite on 2026-08-05
  7. 1680 IMS documents name 24.229 as the document they change IMS documents whose change-request column names 24.229, asked of /var/www/whatthespec.net/data/database/api/api.sqlite on 2026-08-05, of which 1675 are of type CR, CR pack or draftCR
  8. why IMSProtoc2 was proposed the opening sentences of the justification of the work item description /var/www/whatthespec.net/data/data/wis/360029/CP-080794/CP-080794.md, copied word for word, read 2026-08-05. That file was taken as this work item's own because its name begins with CP-080794, the document the work plan points at
  9. 374 different names appear as the writer of an IMS document distinct values of the source column over the IMS documents, asked of /var/www/whatthespec.net/data/database/api/api.sqlite on 2026-08-05. Same caution: the column is free text
  10. Ericsson filed 602 IMS documents IMS documents grouped by the source column, largest first, asked of /var/www/whatthespec.net/data/database/api/api.sqlite on 2026-08-05. The column is the name the document spelled, so one company under two spellings counts twice and no name was resolved to a parent company
  11. Ericsson / Nevenka filed 130 IMS documents IMS documents grouped by the source column, largest first, asked of /var/www/whatthespec.net/data/database/api/api.sqlite on 2026-08-05. The column is the name the document spelled, so one company under two spellings counts twice and no name was resolved to a parent company
  12. the earliest IMS document on record went up on 2015-01-23 the smallest upload stamp over the IMS documents that is 1999-01-01 or later. This is where the store's work item labelling begins and not where IMS work began: the work plan's own Rel-5 rows carry planned days from 2000-01-03, asked of /var/www/whatthespec.net/data/database/api/api.sqlite on 2026-08-05

Every source this course is built on

Check yourself

Answers appear when you pick one, with where they come from.

Q3.1 Which group has the most IMS documents in this register?

Q3.2 What kind of document is most of the IMS pile?

Q3.3 How many different names appear as the writer of an IMS document?

Q3.4 The earliest IMS document on record went up on 2015-01-23. What does that mean?

This chapter was built from a source register generated 2026-08-05. A fresher build of the register may hold different numbers.