Every question of this course

Q1.1 Which of the four documents defines the call control protocol built on SIP and SDP?

• TS 23.228
• TS 22.228
• TS 24.229

TS 24.229's own scope says it defines a call control protocol for the IM CN subsystem based on the Session Initiation Protocol and the associated Session Description Protocol. the scope of 24.229

Q1.2 What do the documents mean by an IP multimedia session?

• A set of multimedia senders and receivers and the data streams flowing between them
• A single voice call between two people
• Any connection a phone opens to the internet

TS 22.228 defines it as a set of multimedia senders and receivers and the data streams flowing from senders to receivers. "IP multimedia session" as 22.228 defines it

Q1.3 What does access independence mean in TS 22.228?

• That any vendor's equipment can be swapped for any other
• That subscribers can reach their IP Multimedia services over any access network that provides IP connectivity
• That IMS works without a subscription

The definition is about the access network, and any one capable of providing IP-connectivity will do. "Access independence" as 22.228 defines it

Q1.4 What is a data channel application, as TS 23.228 defines it?

• A second SIP session opened beside the call
• A separate app a subscriber installs from a store
• An HTML page with JavaScript that the network downloads to the device

The definition reads "A HTML page including JavaScript(s) and optionally image(s) and style sheet(s)", downloaded from the network through the bootstrap data channel. "Data channel application" as 23.228 defines it

Q2.1 How many work plan rows of this subject are marked Rel-5?

• 45
• 14
• 64

The acronym rule takes in 14 Rel-5 rows — the row called IMS and thirteen others around it. 14 IMS work plan rows are marked Rel-5

Q2.2 What does the document store hold for SP-000216, the paper the work plan points at?

• Its title and a summary of what it proposed
• Nothing at all
• The number, the meeting and the file address, and no title

SP-000216 is one of the 32 opening papers the store carries no title for, so it may be cited and not named. SP-000216

Q2.3 What did the founding work item give as its objective?

• To define concepts regarding general service requirements and service features for Release 2000
• To make IMS work over the 5G core
• To write the SIP profile the phone would use

The objective names Release 2000 — an evolved Release 99 plus IM services — and says the services must support multiple media components per call. what IMS set out to do

Q2.4 The earliest IMS document in this record went up on 2015-01-23. What does that day mark?

• The day Release 5 was finished
• Where the store's work item labelling begins
• The day the first IMS work item was opened

It is a floor in the store and not a fact about the work, because the Rel-5 rows themselves carry planned days from 2000. the earliest IMS document on record went up on 2015-01-23

Q3.1 Why did Release 6 open interworking between IMS and circuit-switched networks?

• So that IP-based multimedia could support basic voice calls to and from PSTN, ISDN and GSM/UMTS circuit networks
• Because the IETF asked 3GPP to do it
• Because the codecs were not finished in time

The justification names those networks one by one, and says the capability of IP-based multimedia services would have to reach them. why IMS-CCR-IWCS was proposed

Q3.2 What does the Release 15 work item record SA2 as having agreed about voice on 5G?

• That voice would wait for a later release
• That voice would still be provided by IMS, with the 5G core underneath it as a new kind of IP connectivity
• That voice would move out of IMS and into the 5G core

The justification says the voice services should still be provided by the IMS network and that the 5G core provides a new type of IP-CAN for reaching it. why 5GS_Ph1-IMSo5G was proposed

Q3.3 Why did the first 5G core work leave the existing IMS largely alone?

• IMS was expected to be retired
• Nobody had asked for IMS on 5G
• The scope was kept small on purpose, to avoid a major IMS re-specification that might have delayed the first 5G core specifications

The Rel-16 study says exactly that about the earlier normative work, and then opens the question again. why FS_eIMS5G was proposed

Q3.4 How many work plan rows of this subject are marked Rel-12?

• 60
• 13
• 45

Rel-12 carries 60 rows — the WebRTC and telepresence release, and more rows than Rel-9's 45. 60 IMS work plan rows are marked Rel-12

Q3.5 What did the WebRTC work item set out to specify?

• A new codec for browsers
• Service requirements for WebRTC clients to reach IMS, reusing IMS client credentials and public identities where that made sense
• A replacement for SIP

The objective is a requirements statement about access rather than a new protocol — browsers reaching the IMS a subscriber already has. what IMS_WebRTC set out to do

Q4.1 Which group has the most IMS documents on the local record?

• CT1, with 2169
• SA2, with 429
• The CT plenary, with 221

CT1 has 2169 documents over 66 meetings, the largest count of any group in this record. CT1

Q4.2 What does the shape of the group counts say about this subject?

• It is radio work
• It is core-network work — the three largest counts all belong to CT working groups
• It is charging and management work

CT1 with 2169, CT4 with 746 and CT3 with 719 are the top three, and all three are core-network protocol groups. CT4

Q4.3 What is on the record for RAN2?

• A liaison sent to another group
• The second-largest count after CT1
• One document, at meeting R2-92, tagged IMS-CODEC — and the register does not say what kind of document it is

RAN2 has exactly one IMS document. Calling it a change request or a liaison would be inventing a field the register does not hold. RAN2

Q4.4 Which single meeting handled more IMS documents than any other?

• CT1#112, with 206
• SA2#175
• CT4#135

C1-112, in West Palm Beach in August 2018, handled 206 of them — more than any other single meeting in this record. C1-112 handled 206 IMS documents, more than any other single meeting

Q4.5 Why can the company counts in this chapter not simply be added up per company?

• Because the register leaves out the smaller filers
• Because the column is free text, so one company under two spellings counts twice
• Because documents are filed anonymously

Ericsson appears both as "Ericsson" with 602 and as "Ericsson / Nevenka" with 130, and nothing resolved either name to a parent company. Ericsson / Nevenka filed 130 IMS documents

Q5.1 Which single document do more IMS documents change than any other?

• TS 24.229, the SIP and SDP call control protocol
• TS 23.228, the stage 2 description
• TS 29.562, the HSS services of the 5G system

1680 IMS documents name TS 24.229 as the document they change. TS 23.228 is named by 92 and TS 29.562 by 230. 1680 IMS documents name 24.229 as the document they change

Q5.2 How does a specification get into the 241 at all?

• It carries the letters IMS in its title
• A work item names it as one it will change, or at least three IMS documents name it in the change-request column
• Its owning group asks for it to be listed

Those are the two ways in, and both are read out of the data. A title is never tested, because titles do not say what a document is used for. 241 specifications this work touches

Q5.3 What may this course say about TR 23.794, the Rel-16 study on IMS and the 5G core?

• Its clauses can be cited like any other document's
• Nothing at all
• It can be named and counted, and never quoted — there is no parsed text for it here

72 of the 241 specifications have no parsed text on this machine. TR 23.794 is one of them, so its 190 documents may be counted and its words may not be used. TR 23.794

Q5.4 TS 23.218 and TS 22.173 carry no IMS document at all in the local record. What follows from that?

• Only that no document in the record names them in the change-request column — work item descriptions name both
• That both were withdrawn
• That neither is an IMS document

A zero here is a zero in one column of one store. Both documents are named by work item descriptions as documents that would be changed. TS 23.218

Q5.5 Which document is the second-largest target in this register?

• TS 29.163, interworking with circuit-switched networks
• TS 29.562, the HSS services of the 5G system
• TS 23.228, the stage 2 description of IMS

230 IMS documents name TS 29.562, after TS 24.229's 1680. TS 29.163 has 228 and TS 23.228 has 92. TS 29.562

Q6.1 3509 of the 4939 IMS documents are change requests. What does that mix say about the work?

• Most of it is editing text that is already published
• Most of it is writing the text of new study reports
• Most of it is letters between one group and another

A change request is the only way a published specification is ever altered. A pile that is mostly change requests is a pile of upkeep. 3509 IMS documents are of type CR

Q6.2 How often has the IETF protocol alignment work been reopened?

• Only when the IETF publishes a new protocol document
• In every release since Rel-7, from IMSProtoc through to IMSProtoc20-CT
• Once, in Rel-8, and never again

The work plan carries a numbered continuation of it in every release from Rel-7 to Rel-20. IMSProtoc20-CT

Q6.3 FS_IMSRE_SEC has the word Deleted written at the front of its own name. What else is true of it?

• It was renamed FS_IMSResil
• Nothing else — the row is empty
• It has an approved study paper, SP-251237, and 16 meeting documents against it

Both facts sit on the same row, and writing one without the other misleads. Deleted is hand-written into the title, not a status field. FS_IMSRE_SEC

Q6.4 What did the Rel-19 resiliency study say it was for?

• A more stable IMS network — fewer accidents, and a better restoration mechanism when one happens
• Carrying AI and machine-learning data inside a call
• Aligning 3GPP's use of SIP with the IETF

That is the objective in the proposers' own words in CP-232281, the paper that opened FS_IMS_RES. what FS_IMS_RES set out to do

Q6.5 The Rel-8 and the Rel-20 phases of the protocol alignment open with the same justification. What changed between them?

• The Rel-20 phase carries no justification at all
• One word — "provides" became "provided"
• The whole justification was rewritten around 5G

Both open "In Release 5, the IMS was defined to support IP Multimedia services", and the second sentence differs only in that tense. why IMSProtoc20-CT was proposed

Q7.1 What is the right thing to type into a 3GPP document search to follow this work?

• The work item acronym, such as IMSProtoc20-CT
• The name of the company that proposed it
• The phrase "IP Multimedia Subsystem"

Every document is filed against a work item acronym. A title search misses work whose title never says IMS. 177 different work item acronyms carry IMS

Q7.2 IMS_Corp2 is IMS work. What is it called in the work plan?

• IMS business trunking
• Transfer of ETSI business trunking specifications — the letters IMS are not in the title at all
• IMS corporate networks, phase 2

Its acronym carries IMS and its title does not. That is why nothing in this register was picked by reading a title. IMS_Corp2

Q7.3 339 of the 345 work plan rows stand at 100 per cent complete. What does that tell you?

• That 339 work items are finished
• That the other six were cancelled
• Only that a percentage kept by hand reads 100 — there is no status field for a work item anywhere in this data

The completion figure is the work plan's own bookkeeping. No store here records whether a piece of work is running, stopped or finished. 339 of the 345 IMS work plan rows stand at 100%

Q7.4 The earliest IMS document on record went up on 2015-01-23. What does that date mark?

• Where this store's work item labelling begins — the work itself starts at Rel-5, long before
• The day TS 23.228 was first published
• The day IMS work began

It is a floor in a database, not a beginning in the world. Every document count in this course is a floor for the same reason. the earliest IMS document on record went up on 2015-01-23

Q7.5 The Rel-20 architecture study sits under two document numbers. What should a reader do with that?

• Use TR 23.801-04, because the documents name it
• Carry both — the work item names 23.801-03, 47 documents name 23.801-04, and nothing here settles which is right
• Use TR 23.801-03, because the work item description names it

The two numbers disagree in the data itself, and picking one quietly would hide a real conflict rather than report it. TR 23.801-04