In-Dialog Method (Optional) - ETSI TS V3.5.1 ( )

D.2.1 Actions at the originating VGW/AGCF

D.2.1.1 Terminating overlap signalling at originating VGW/AGCF

If overlap sending is used, the SETUP message contains either: a) no called number information;

b) incomplete called number information; or

When the VGW/AGCF has received called number information element from the calling user in a SETUP message (possibly followed by INFORMATION messages), it shall send an INVITE request with all the available called number information in the Request line and the originating SDP (derived from the BC and optionally present HLC for the VGW - else as obtained from the originating AGW (and influenced by the BC and optionally present HLC)) - see

table 5.1.1.1.4-2.

The AGCF/VGW can contain a configurable digit map which is used to analyse the Called party information element contents received in a sequence of Called party number information elements. Among other purposes, this digit map can be used to:

• identify the required number of digits to be entered for a particular digit sequence. The procedures for digit maps are described within TS 183 043 [42], clause 7.3.1.3.1.1.

Even in the absence of a digit map, it is appropriate for the AGCF/VGW to collect dialled digits. The AGCFVGW shall contain a configurable parameter indicating the minimum number of digits expected in the sequence of Called party number information elements before a Request-URI is constructed and an INVITE request sent. The minimum number could be zero.

D.2.1.2 Sending of INVITE without determining the end of address signalling

On receipt of such a SETUP message, the AGCF/VGW starts the ISDN timer T₃₀₂, sends a SETUP ACKNOWLEDGE message to the user and enters the overlap sending state:

• If no number information is included the network will return dial tone, if required by the tone option. • If the received BC in the SETUP message is coded with speech, 3,1 kHz audio, UDI/TA, it shall include

progress indicator No. 8, in-band information or appropriate pattern is now available, in the SETUP ACKNOWLEDGE message.

1) As a network option, the originating VGW/AGCF may send INVITE requests without determining the end of address signalling. If the originating VGW/AGCF sends an INVITE request before the end of address signalling is determined, the originating VGW/AGCF:

- use the SIP precondition extension within the INVITE request; - be prepared to process INFO as described below;

- be prepared to handle incoming SIP 484 (Address Incomplete) responses; - on receipt of 404 Not Found or 484 Address Incomplete start timer Tisdn3. 2) On receipt of a new INFO from the DSS1 side, the AGCF/VGW shall:

- if an early dialog has been established, send a SIP INFO request including the additional digits for this call;

- if an early dialog has not been established, wait for a final error response for the previous INVITE and send an INVITE request including all digits received so far for this call in the Request-URI.

At the receipt of a new DSS1 INFO message, a SIP 18x provisional response, or a SIP 200 OK (INVITE), the originating VGW/AGCF shall stop Tisdn3.

As a network option the Timer T_info can be used , in this case the following procedure apply starting with the first digit received by the AGCF/VGW:

• start timer T_info with receiving the SETUP; • collect all digits received within INFO messages;

• at expiry of timer T_info the initial INVITE is sent out as described under 1):

- If further digits are needed then the AGCF/VGW shall collect further digits until min length has been reached.

As a network Option the first INVITE can be sent with the receipt of the SETUP message and the T_infois started. The timer T_info shall not be used if the INVITE has to be sent immediately because e.g. the hotline feature is provided to the originating user.

The originating VGW/AGCF shall send a RELEASE message with Cause Value 28 towards the ISDN user if Tisdn3 expires.

Option a) Overlap with T_info Timer.

AGCF/VGW

x-CSCF

SETUP

INVITE Cseq 1

SETUP ACK

INFO

T

Info

INFO

183 Session Progress Cseq 1

CALL PROCEEDING

INFO

AGCF/VGW

x-CSCF

SETUP

INVITE Cseq 1

SETUP ACK

INFO

T

Info

INFO

CALL PROCEEDING

INFO Cseq 2

200 Cseq 2

INFO

183 Session Progress Cseq 1

Option b) Overlap with Digit Map.

AGCF/VGW

x-CSCF

SETUP

INVITE Cseq 1

SETUP ACK

INFO

183 Session Progress Cseq 1

CALL PROCEEDING

INFO Cseq 2

200 Cseq 2

INFO

Digit map matched

183 Session Progress Cseq 1

INFO Cseq 3

200 Cseq 3

Option c) Overlap with Digit Map and T_info Timer.

AGCF/VGW

x-CSCF

SETUP

INVITE Cseq 1

SETUP ACK

INFO

183 Session Progress Cseq 1

CALL PROCEEDING

INFO Cseq 2

200 Cseq 2

INFO

Digit map matched

Stop T

Info

T

Info

INFO Cseq 3

200 Cseq 3

183 Session Progress Cseq 1

Figure D.2.1.2-4: Overlap with digit map and Tinfo timer digit map matched before T_info expiry

AGCF/VGW

x-CSCF

SETUP

INVITE Cseq 1

SETUP ACK

INFO

183 Session Progress Cseq 1

CALL PROCEEDING

INFO

Digit map matched

T

Info

INFO

INFO Cseq 2

200 Cseq 2

183 Session Progress Cseq 1

Figure D.2.1.2-5: Overlap with digit map and Tinfo timer digit map matched after T_info expiry

Option d) 484 message with Min-length X parameter.

Option c) 484 message without Min-length X parameter.

Figure D.2.1.2-7: 484 message without Min-length X parameter

D.2.2 Actions at the terminating VGW/AGCF

See annex H for DDI. For all other no further action is needed.

Annex E (normative):

Direct Dialling in

This annex describes the handling of Direct Dialling In.

In document ETSI TS V3.5.1 ( ) (Page 108-117)