Content for TS 23.079 Word version: 18.0.0

1 Scope p. 5

The present document specifies the technical realisation of the first phase of the network feature Support of Optimal Routeing (SOR). The first phase of SOR provides:

as a network operator option, a method to route a call from one mobile subscriber directly to another mobile subscriber who is in the same country as the calling mobile subscriber or in the called mobile subscriber's home country, without needing to connect the call via the HPLMN of the called subscriber, even though the called mobile subscriber has roamed outside his HPLMN;
a method to forward calls when a called mobile subscriber who has roamed outside his home country is busy, or is not reachable, or does not reply, to a forwarded-to destination in the HPLMN country of the called subscriber or the VPLMN country of the called subscriber, without needing to connect the forwarded call via the VPLMN of the called subscriber;
a method to combine the optimal routeing described in the first bullet point above with the optimal routeing described in the second bullet point above.

OR of a call is permitted only if all entities involved in handling the call support OR.

Other cases of optimal routeing (e.g. calls where the calling and called subscribers are in different countries, forwarding to a mobile subscriber or multiple forwarding) will be considered for inclusion in later phases.

2 References p. 5

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.

References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
For a specific reference, subsequent revisions do not apply.
For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.

[1]

GSM 03.04: "Digital cellular telecommunications system (Phase 2+); Signalling requirements relating to routeing of calls to mobile subscribers".

[2]

TR 21.905: "Vocabulary for 3GPP Specifications".

[3]

TS 22.079: "Support of Optimal Routeing (SOR); Service definition - Stage 1".

[4]

TS 22.082: "Call Forwarding (CF) supplementary services - Stage 1".

[5]

TS 23.003: "Numbering, addressing & identification".

[6]

TS 23.018: "Basic call handling; Technical realization".

[7]

TS 23.078: "Customized Applications for Mobile network Enhanced Logic (CAMEL) - Phase 3; Stage 2".

[8]

TS 23.085: "Closed User Group (CUG) Supplementary Service - Stage 2".

[9]

TS 23.087: "User -to-User Signalling (UUS) - Stage 2".

[10]

TS 23.172: "Technical realization of Circuit Switched (CS) multimedia service; UDI/RDI fallback and service modification"

3 Definitions and abbreviations p. 6

3.1 Definitions p. 6

For the purposes of the present document, the following terms and definitions apply.

A subscriber:

calling subscriber, who may be fixed or mobile

B subscriber:

mobile subscriber originally called by the A subscriber

C subscriber:

subscriber to whom the B subscriber has requested that calls be forwarded. The C subscriber may be fixed or mobile

Direct route:

call takes the direct route if the route from the serving PLMN of the A subscriber to the serving PLMN of the B subscriber is defined by the MSRN of the B subscriber rather than by the MSISDN of the B subscriber

Early call forwarding:

call forwarding from the IPLMN before the call has been extended to the VPLMN of the forwarding subscriber

HPLMN leg:

portion of the HPLMN route from the serving MSC of the A subscriber to an MSC in the HPLMN of the B subscriber

HPLMN route:

call takes the HPLMN route if the route from the serving MSC of the A subscriber to the serving MSC of the B subscriber is defined by the MSISDN of the called subscriber. This forces the call to be routed via the HPLMN of the B subscriber

Interrogating PLMN (IPLMN):

PLMN which interrogates the HPLMN of the B subscriber to obtain information to route the call to that subscriber or to the forwarded-to destination defined by the called mobile subscriber. The IPLMN is also the VPLMN of the A subscriber

Late call forwarding:

call forwarding after the call has been extended to the VPLMN of the forwarding subscriber. Late call forwarding may be invoked in the IPLMN or the VPLMN of the forwarding subscriber

Reference address:

address which defines the maximum charge which the A party is prepared to pay for the call leg which he originates

Routeing address:

address which the GMSC uses to route a call towards the B subscriber or the C subscriber

3.2 Abbreviations p. 7

Abbreviations used in the present document are listed in TS 21.905.

For the purposes of the present document, the following abbreviations apply:

BOIZC

Barring of Outgoing InterZonal Calls

BOIZC-exHC

Barring of Outgoing InterZonal Calls except those directed to the HPLMN Country

CMN

CAMEL Modified Number

FTN

Forwarded-To Number

FTNW

Forwarded-To NetWork

GMSCA

The GMSC in the IPLMN, which may also be VMSCA

GMSCB

The GMSC in HPLMNB

GMSCC

The GMSC in HPLMNC

HLRB

The HLR of the B subscriber

HLRC

The HLR of the C subscriber

HPLMNB

The HPLMN of the B subscriber

HPLMNC

The HPLMN of the C subscriber

IAM

Initial Address Message

IPLMN

Interrogating PLMN

ORLCF

Optimal Routeing for Late Call Forwarding

PRN

Provide Roaming Number

PSI

Provide Subscriber Information

RCH

Resume Call Handling

SIFIC

Send Information For Incoming Call

SIFOC

Send Information For Outgoing Call

SRI(B)

Send Routeing Information (Basic call)

SRI(F)

Send Routeing Information (Forwarding information)

VLRA

The VLR of the A subscriber

VLRB

The VLR of the B subscriber

VMSCA

The VMSC of the A subscriber

VMSCB

The VMSC of the B subscriber