Explicit Communication Transfer (ECT)

5.2.7.1

Actions at the Outgoing AGCF/VGW

For this service, the separation "incoming call" and "outgoing call" does not apply.

This clause describes the interworking at the AGCF/VGW (i.e. the exchange where the served user is connected to). To simulate ECT in the IMS, the Consultative Transfer is applicable.

5.2.7.1.1

Coincident S and T reference point

5.2.7.1.1.1 Service invocation

The invocation of ECT in the alerting state should be rejected by the AGCF/VGW.

Table 5.2.7.1.1.1-1: ECT invocation

Message received from the served user (user A)

REFER FACILITY→

Facility information element EctExecute invoke component or

ExplicitEctExecute invoke component

The request URI shall contain the SIP URI of the transferee as received in the Contact header field.

The Refer-To header field shall indicate the public address of the transfer Target.

A Replaces header field parameter shall be added to the Refer-To URI together with a Require=replaces header field parameter. Method=INVITE.

The ECT procedures are performed by the Application Server and described in TS 183 029 [36] As a network provider option: The REFER may be interworked in a reINVITE to the Transferee and to the Transfer target. These special REFER handling procedures are described in the TS 183 028 [32].

5.2.7.1.2

T reference point

5.2.7.1.2.1 Service invocation

Receipt of a notification from the access:

Table 5.2.7.1.2.1-1: Receipt of a notification from the access

Message received from the access FACILITY→

Facility information element EctInform invoke component

alerting

No mapping FACILITY→

Facility information element EctInform invoke component

active

redirectionNumber (see note)

Facility information element (see note) SubaddressTransfer invoke component

No mapping

NOTE: The Access transport parameter is not interworked sent if the SubaddressTransfer invoke component is received.

5.2.7.2

Actions at the incoming AGCF/VGW

For this service, the separation "outgoing call" and "incoming call" does not apply.

This clause describes the interworking at the O/I-AGCF/VGW (i.e. the AGCF/VGW where the remote user(s) is(are) connected to).

5.2.7.2.1

Coincident S and T reference point

5.2.7.2.1.1 Messages received from the network

5.2.7.2.1.1.1 Receipt of an INVITE/UPDATE message

The ECT simulation service is performed as described in TS 183 029 [36] with the additions and clarifications described in TS 183 028 [32] in special REFER handling procedures.

Upon receipt of an INVITE or UPDATE:

a) reINVITE the corresponding remote ECT user is in alerting state

NOTE 1: This interworking is applicable to the user in "active call state, call held auxiliary state" when the corresponding remote ECT user is in alerting state.

Table 5.2.7.2.1.1.1-1: INVITE/UPDATE

Message received from the network

INVITE → No mapping No mapping

b) reINVITE the corresponding remote ECT user is in answered state

NOTE 2: This interworking is applicable to the user in "active call state, call held auxiliary state" or "active call state, idle auxiliary state" or "call delivered state" when the corresponding remote ECT user is in answered state.

Table 5.2.7.2.1.1.1-2: INVITE/UPDATE

INVITE →

INVITE P-Asserted-Identity

Privacy absent or not "id"

Connected Subaddress information element as isub parameter in the P-Asserted- Identity

No mapping

Other cases (see note 2)

No mapping

NOTE 1: This can only occur in case of interaction of ECT with ECT. NOTE 2: Other cases:

- no subaddress in the reINVITE; or - Privacy header value "id"; or

- no P-Asserted-Identity in the reINVITE.

Table 5.2.7.2.1.1.1-3: INVITE/UPDATE

INVITE/UPDATE not completing a

Call transfer, alerting

notification INVITE/UPDATE →

P-Asserted-Identity (see note 2)

No mapping No mapping

NOTE 1: This can only occur in case of interaction of ECT with ECT. NOTE 2: The P-Asserted-Identity may be absent.

5.2.7.2.1.1.2 Receipt of a UPDATE message for a call in alerting phase

This clause applies only for a call in alerting phase. One case is possible:

UPDATE

Upon receipt of such a message, one case is possible:

Table 5.2.7.2.1.1.2-1: UPDATE

UPDATE →

P-Asserted-Identity, Privacy

header absent or not "id". Connected Subaddress information element as isub parameter in the P-Asserted-Identity No mapping Other cases (see note 2) No mapping

NOTE 1: This can only occur in case of interaction of ECT with ECT. NOTE 2: Other cases:

- no subaddress in the UPDATE; or - Privacy header value "id"; or

- no P-Asserted-Identity present in the UPDATE.

Table 5.2.7.2.1.1.2-2: UPDATE

UPDATE not completing a

call-transfer-alerting notification

UPDATE→

P-Asserted-Identity

No mapping

5.2.7.2.2

T reference point

5.2.7.2.2.1 Service invocation: Messages received from the network

5.2.7.2.2.1.1 Receipt of an INVITE/UPDATE

Upon receipt of an INVITE or UPDATE, two cases are possible: a) INVITE the corresponding remote ECT user is in alerting state

NOTE 1: This interworking is applicable to the user in "active call state, call held auxiliary state" when the corresponding remote ECT user is in alerting state.

b) INVITE the corresponding remote ECT user is in answered state

NOTE 2: This interworking is applicable to the user in "active call state, call held auxiliary state" or "active call state, idle auxiliary state" or "call delivered state" when the corresponding remote ECT user is in answered state.

Table 5.2.7.2.2.1.1-1: INVITE/UPDATE

INVITE/UPDATE →

P-Asserted-Identity

Privacy header absent or value is not "id"

Connected Subaddress information element as isub parameter in the P-Asserted- Identity

No mapping

Other cases (see note)

No mapping

NOTE: Other cases:

- no subaddress in the reINVITE; or - Privacy header value "id"; or

- no P-Asserted-Identity present in the reINVITE.

5.2.7.2.2.1.2 Receipt of a UPDATE for a call in alerting phase

One case is possible: • UPDATE. a) UPDATE

Table 5.2.7.2.2.1.2-1: UPDATE

UPDATE →

P-Asserted-Identity, Privacy

header absent or value not "id" Connected Subaddress information element as isub parameter in the P-Asserted- Identity

No mapping

Other cases (see note)

No mapping

NOTE: Other cases:

- No subaddress in the UPDATE; or - Privacy header value "id"; or

- No P-Asserted-Identity present in the UPDATE.