2.1 Introduction

2.2 Supplementary Service Operation Summary

2.3 Supplementary Service Participants

2.4 Supplementary Services Under ETS 300

2.4.1 Using Supplementary Services (ETS 300)

2.4.2 Hold and Retrieve Services (ETS 300)

2.4.3 Call Transfer Services (ETS 300)

2.4.4 Call Forwarding Services (ETS 300)

2.4.5 Advice of Charge (ETS 300)

2.4.6 Call Identification Services (ETS 300)

2.5 Supplementary Services Under Q.SIG

2.5.1 Using Supplementary Services (Q.SIG)

2.5.2 Tandem Services (Q.SIG)

2.5.3 Transfer Services (Q.SIG)

2.5.4 Call Forwarding Services (Q.SIG)

2.5.5 Call Identification Services (Q.SIG)

2.1 Introduction

This chapter:

• Summarizes the supplementary service operations available across the Q.SIG and ETS 300 variants.

• Provides an overview of the supplementary services implemented under each variant.

2.2 Supplementary Service Operation Summary

The following table summarizes the supplementary service operations available across the variants.

Supplementary Service Operation	ETSI	Q.SIG	Documented In
Invoke Bridge Calls	-	X	Chapter 4
Invoke Call Hold	X	-	Chapter 5
Invoke Call Retrieve	X	-	Chapter 5
Notify Hold	X	X	Chapter 5
Notify Retrieve	X	X	Chapter 5
Explicit Call Transfer	X	-	Chapter 6
Notify Transfer	X	X	Chapter 6
Invoke Call Diversion	-	X	Chapter 7
Activate Diversion	X	-	Chapter 7
Deactivate Diversion	X	-	Chapter 7
Enquire Diversion	X	-	Chapter 7
Remind Diversion	X	-	Chapter 7
Notify Diversion	X	X	Chapter 7
Invoke Call Deflection	X	-	Chapter 7
Activate Deflection	X		Chapter 7
Deactivate Deflection	X		Chapter 7
Advice of Charge Request	X	-	Chapter 8
Advice of Charge Inform	X	-	Chapter 8
Calling Name Identification Presentation (CNIP)	-	X	Chapter 9
Connected Name Identification Presentation (CONP)	-	X	Chapter 9
Calling Line Identification Presentation (CLIP)	X	X	Chapter 9
Calling Line Identification Restriction (CLIR)	X	X	Chapter 9
Connected Line Identification Presentation (COLP)	X	X	Chapter 9
Connected Line Identification Restriction (COLR)	X	X	Chapter 9

2.3 Supplementary Service Participants

Three parties are identified in the activation or invocation of a supplementary service:

• The served user: The user or node which activates or invokes the supplementary service. If the service is billable, then this is the user or node charged for it.

• The originating user: The user or node who originated the call into the network.

• The diverted-to user: In call forwarding services, this is the user or node to which the call is rerouted.

2.4 Supplementary Services Under ETS 300

This section provides an overview of the supplementary services available with the ETS 300 variant, and how these services operate in the network architecture.

2.4.1 Using Supplementary Services (ETS 300)

Under ETS 300, most supplementary services require subscription. Subscription services are optional services provided by the network operator on a provisioning basis. When the user requests network services from a provider, he/she also can optionally request one or more subscription services. The services are not available unless the interface is provisioned with them.

Note: Some supplementary services may not require subscription. For example, the Call Hold service may be generally available.

Under ETS 300, most supplementary services must be activated before they are used. Activation is the process of "turning on" the service at the network or stack level. Once a service is activated, the network, the stack and/or the application can invoke (use) the service when needed.

A supplementary service can be activated in at least one of the following ways:

• Some supplementary services are activated the moment they are subscribed to. The Remind Diversion service is one of these. To deactivate this service, the service provider must be contacted.

• Other supplementary services are activated or deactivated by the application as necessary. The Call Diversion service is an example: the application can activate it to configure the network to automatically forward a user's calls.

• Many supplementary services can be set up either way. For example, when subscribing to Advice of Charge (AOC) services, the user can specify that the service is active at all times. Alternatively, they can be configured so they are active only when the application requests an activation.

The act of using an activated supplementary service is called invocation of the service. In some cases, an application can automatically activate an inactive supplementary service by invoking it: the activation and invocation occur simultaneously. The Explicit Call Transfer service is an example: the application can invoke this service on a call-by-call basis.

2.4.2 Hold and Retrieve Services (ETS 300)

An application on the user side of the S/T reference point may invoke Hold and Retrieve services on the network. When a call (identified by its connection ID) is placed on hold, the bearer channel (B channel) resource for the call is deallocated without losing the context of the call. The network side of the S/T reference point then reserves the B channel for allocation in a subsequent call offered by the user side.

The following hold and retrieve operations can be performed under ETS 300:

• Invoke Call Hold - the application requests the network to put a call on hold.

• Invoke Call Retrieve - the application requests the network to retrieve a call on hold.

• Notify Hold - the network informs a party that it is on hold.

• Notify Retrieve - the network informs a held party that it has been retrieved.

For more information, see Chapter 5.

2.4.3 Call Transfer Services (ETS 300)

Call Transfer services allow an application at the user side of the S/T reference point to cause two existing calls to be joined together on the network side.

The following call transfer operations can be performed under ETS 300:

• Invoke Explicit Call Transfer - the application requests the network to join two existing calls together.

• Notify Transfer - the network notifies the joined users when a call has been affected by a remote transfer.

2.4.4 Call Forwarding Services (ETS 300)

Under ETS 300, two types of call forwarding services are available: Call Diversion and Call Deflection.

Call Diversion is activated by the served user application on the network for all calls for a specific user or trunk. With this service active, the network reroutes calls addressed to a specific user or trunk, without consulting the user side of the S/T reference point. Three types of call diversion are supported: Call Forwarding - Unconditional, Call Forwarding - Busy, and Call Forwarding - No Response.

The following Call Diversion operations can be performed under ETS 300:

• Activate Diversion - activates Call Diversion on all calls on a user or trunk.

• Deactivate Diversion - deactivates Call Diversion on a specific user or trunk.

• Notify Diversion - when a diversion or deflection occurs, the network notifies the diverted-to user or trunk of the rerouting operation.

• Enquire Diversion - the served user application can enquire the network, to learn the status of the Call Diversion service for a given user or trunk, or for all users/trunks.

Call Deflection can be activated for all calls, or activated on a call-by-call basis. When invoked, the served user stack (not the network) deflects (redirects) the call to a new destination. With this service, the user side can deflect a call to a different destination, without first answering it.

The following Call Deflection operations can be performed under ETS 300:

• Activate Deflection - activates Call Deflection for all calls on a specific trunk.

• Deactivate Deflection - deactivates Call Deflection on a specific trunk.

• Invoke Deflection - invokes Call Deflection on a specific call.

A special Remind Diversion service can also be activated for an ETS 300 application, on a subscription basis. When a served user initiates an outbound call, this service causes the network to remind the served user if Call Diversion has been activated for incoming calls.

2.4.5 Advice of Charge (ETS 300)

Advice of Charge (AOC) provides the user with a way of tracking the costs of a specific call, in real time. Three separate AOC services are available, depending upon at what point the application requires AOC information:

• AOC at start of call (AOC-S)

• AOC during the call (AOC-D)

• AOC at end of call (AOC-E)

The following Advice of Charge operations can be performed under ETS 300:

• Advice of Charge Request - requests the network to invoke Advice of Charge services for a specific call.

• Advice of Charge Inform - invoked by the network to pass Advice of Charge information to the application.

2.4.6 Call Identification Services (ETS 300)

The following identification services are implemented in NMS ISDN for the ETS 300 variant:

• Calling Line Identification Presentation (CLIP): The called party receives the calling party's address information.

• Calling Line Identification Restriction (CLIR): Prevents the calling party's address information from being presented to called users.

• Connected Line Identification Presentation (COLP): Allows the calling party to determine the connected party's address information.

• Connected Line Identification Restriction (COLR): Restricts the calling party from determining the connected party's address information.

2.5 Supplementary Services Under Q.SIG

This section provides an overview of the supplementary services available with the Q.SIG variant, and how these services are implemented in the network architecture.

2.5.1 Using Supplementary Services (Q.SIG)

Q.SIG applications provide supplementary services as part of their basic duties: the "subscription" concept has no meaning at this level. All supported services are activated at all times: a Q.SIG application need only invoke a service in order to use it.

2.5.2 Tandem Services (Q.SIG)

Tandem services support the transit node role. A transit node is an intermediate step in a call being set up through a network. A PINX may take on the responsibilities of a transit node during the call setup procedures, as a result of routing decisions, or it may happen as a result of supplementary service activation (e.g. call transfer). A transit node must maintain two separate basic calls, and additionally, interwork the events from one call into actions on the other call.

NMS ISDN supports the Call Bridging tandem service. When this service is active, all notification and facility information elements are passed from one end to the other through the transit node. However, the application remains responsible for basic call control interaction. for example, the application must handle hanging up.

This service may be invoked in either of two ways:

• Explicitly, using the Invoke Bridge Calls operation.

• Implicitly when the Notify Transfer operation is called, and both transfer parties are remote. Implicit call bridging does not take place if one or both calls are local.

2.5.3 Transfer Services (Q.SIG)

NMS ISDN supports transfer-by-join operations between Q.SIG nodes. In a transfer-by-join operation, the two separate calls are connected through the local node. The local node is still involved in the call (for example, the call was not rerouted).

To transfer a call under Q.SIG, the application must perform the switching required to connect calls together, using standard calls to the Natural Access Switching service. The application also invokes a Notify Transfer operation to notify each remote party that the transfer has taken place.

2.5.4 Call Forwarding Services (Q.SIG)

Under Q.SIG, Call Diversion supports Call Forwarding - Unconditional, Call Forwarding - Busy, and Call Forwarding - No Response.

The following Call Diversion operations are supported under Q.SIG:

• Invoke Call Diversion - the served user node requests the originating node to forward a call.

• Notify Diversion - the originating node notifies the diverted-to node that the call has been forwarded from another user.

2.5.5 Call Identification Services (Q.SIG)

All of the call identification services for the ETS 300 variant (see Section 2.4.6) are also implemented for Q.SIG. In addition, the following Q.SIG-only identification services are implemented in NMS ISDN:

• Calling Name Identification Presentation (CNIP): The called party receives the name of the calling party. Available only under the Q.SIG variant.

• Connected Name Identification Presentation (CONP): The calling party receives the name of the called party. Available only under the Q.SIG variant.