5 Terminal interfacing to GSM 04.08 Mapping

07.023GPPTerminal Adaptation Functions (TAF) for services using asynchronous bearer capabilitiesTS

Only those elements/messages that are of particular relevance are considered.

Interface procedures not directly mappable to GSM 04.08 [5] (i.e. V.25 bis VAL/INV) are not considered. Mobile management procedures of GSM 04.08 [5] are not considered applicable.

Mapping of other call establishment or clearing messages to the S interface e.g. "Call proceeding" etc. have not been included. It is assumed these will be able to be mapped directly and are of no relevance to the V.25 bis or manual interface.

For the Alternate speech/data, Alternate speech/group 3 facsimile and Speech followed by data services it will be necessary for the TAF to generate a "Modify" message for transmission on the Dm channel. This shall be according to the defined procedure in GSM 04.08 [5].

In addition for the Alternate speech/data case it will be necessary for the TAF to respond to an incoming "Modify" command with "Ack" or "Reject".

5.1 Mobile Originated Calls

Call establishment is initiated by the keypad or DTE action:

a) Setup

Element

Derived from

MMI

V.25 bis message

S interface message

Called

Keypad

CRN/CRI/CRS

Setup

Address

Called

Keypad

CRI

Setup

Sub Address

HLC

Derived from internal

Setup

settings or MMI infor‑ mation.

LLC

Same as HLC

Setup

BC

Same as HLC GSM 07.01

Setup (with addi‑

gives

tional information

allowed values

from MMI originated

settings)

b) Release Complete

Element

Derived from

MMI

V.25 bis message

S interface message

Cause

Display

CFI

Release Complete

(optional)

5.2 Mobile Terminated Calls

Call establishment is initiated by receipt of Setup at the MS:

a) Setup

Element

Mapped on to

MMI

V.25 bis message

S interface

message

Called

Display

INC

Setup

Address

(optional)

Called Sub

Display

Not applicable

Setup

Address

(optional)

HLC

Display

Not applicable

Setup

(optional)

LLC

Display

Not applicable

Setup

(optional)

BC

Display

Not applicable

Setup (with PLMN

(optional)

specific elements

removed)

b) Call Confirm

Information for the BC element in the call confirm is derived from e.g. MMI or by internal settings.

c) Connect

Connect is sent in response to connect from the S interface, from MMI, or when the timeout period referred to in V.25bis has expired. This period shall be between 5 and 10 seconds. During this time the automatic answering of the incoming call can be prevented by issuing a DIC command. The CIC can be used to cancel the effect of a preceding DIC command (see Recommendation V.25bis [11]).

5.3 Call Clearing

5.3.1 Mobile initiated

Call clearing is initiated by the keypad or DTE action:

Disconnect

Element

Derived from

MMI

V.25 bis

S interface message

Cause

Keypad

DTE shall turn CT 108/2 OFF

Disconnect

or inband V.110 disconnect request

5.3.2 Network initiated

Call clearing is initiated by receipt of Disconnect at the MS:

Disconnect

Element

Mapped on to

MMI

V.25 bis

S interface message

Cause

Display

(optional)

MS shall turn CT 107 OFF

Disconnect