1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-1000653.1996(R2015) Integrated Services Digital Network (ISDN) Call Park Supplementary Service As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industrys most-press
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11、ll Park Retrieve: Call Park Retrieve allows a user to recover a call from any DN by specifying that Parked DN in the Call Park Retrieve procedures (the Parked DN and Retrieving DN are required to belong to the same CPSG). After invoking Call Park Retrieve, the user may retrieve calls parked against
12、their own DN by the use of an abbreviated indication, for example, pressing the # key; Ring-back After Time-out: Ring-back After Time-out allows the network to offer a parked call to the Parking Party if the call is not unparked within a specified period of time. ATIS-1000653.1996 4 At any given tim
13、e, only one call shall be allowed to be parked against a DN. Call Park is useful when a Parking Party on an active call wishes to physically move to another location for convenience or to locate information. For example, the party may Park the call, walk down to another office, and then recover the
14、Parked call. In this way Call Park serves as an alternative to call transfer perhaps when the user does not know the extension to which to transfer the call. Call Park is also useful in loudspeaker paging applications, and in situations where a secretarial station providing call coverage wishes to p
15、ark a call, locate the desired party for the call, and have that party recover the Parked call. 4.2 Procedures 4.2.1 Provision/withdrawal Call Park services shall be provided on a subscription basis. As a service provider option, Call Park service shall be offered with several subscription options.
16、The Service Provider shall group subscriber lines into Call Park Subscriber Groups, as defined in 3.1.1. Options that shall apply separately to each DN/bearer service, to each TSP, to each DN/bearer service per TSP, or to a Call Park Subscriber Group (CPSG) are shown in table 1. Withdrawal of the se
17、rvice shall be made by the service provider upon request by the subscriber or for service provider reasons. Table 1 Subscription options for Call Park service Subscription options Values Basis Call Park assigned Yes or No Per DN/Bearer Service, TSP, DN/Bearer Service/TSP, or CPSG Ring-back Timer val
18、ue 30 seconds to 6 minutes Per CPSG in increments of 15 seconds Ring-back failure treatment Clear parked call Per CPSG Forward to specified DN Call Park Subscriber Group identifier Identifier DN/Bearer Service Call Park Retrieve indicator Yes or No Per DN/Bearer Service/TSP 4.2.2 Normal procedures 4
19、.2.2.1 Activation/deactivation Call Park service shall be active whenever provided on a subscription basis. There are no user procedures to activate or deactivate Call Park. 4.2.2.2 Invocation and operation The following list identifies the normal procedures for the invocation and operation of the C
20、all Park service: Call Park request: At any time while the served user (Parking Party) has a call in the active state, the served user shall be able to indicate to the network that the call on the interface (the active call) is to be parked, and then shall specify a DN that the call is to be parked
21、against (the Parking and Parked DNs shall belong to the same CPSG). The Parking Party may indicate their own DN as the Parked DN. Instead of indicating a specific DN, the Parking Party may provide an abbreviated indication of the Parked DN in order to park the call ATIS-1000653.1996 5 against their
22、own DN. The network shall allow a call to be parked any time it is in the active state. The network shall acknowledge this action, and park the call against the DN specified by the Parking Party. The communication on the Parking Partys interface shall then be cleared, and the associated channel shal
23、l be made available for other uses. The call shall no longer be associated with the Parking Partys channel, nor shall it be associated with the Parked DNs channel (see figure 1, part 1). If the Parked DN has a Call Park Retrieve indicator assigned, then the user at that DN shall receive an indicatio
24、n that the call was parked against the DN. After a call has been successfully parked, the Ring-back timer shall be started; Call Park Retrieve request: To unpark a call, the served user (Retrieving DN) shall indicate to the network that a call parked against a DN (Parked DN, possibly the same as the
25、 Retrieving DN) is to be reconnected. The user shall provide the Parked DN during the service request procedures. If the user is unparking a call against their own DN, they may provide an abbreviated indication to the network. The DN of the served user shall be required to belong to the same CPSG as
26、 the specified Parked DN. If the network can satisfy the request, the network shall reestablish communications for the call on the requesting users interface, and send an indication to all terminals that have a Call Park Retrieve indicator assigned for the Parked DN (see figure 1, part 2); Ring-back
27、 After Time-out: When a call is successfully parked, the Ring-back timer (T-Rbt) shall be started. If a parked call is not retrieved before timer T-Rbt expires, the network shall attempt to offer the call to the Parking Party as a ring-back call termination. If the Parking Party is busy, then the ne
28、twork shall restart the timer for a second time. This procedure continues up to three times. If the Parking Party is busy on the third offering, the call shall be cleared or forwarded based on a subscription option. If the Parking Party is idle when timer T-Rbt expires, the call shall be offered to
29、the Parking Party as a ring-back call termination and timer T-Arb shall be started. The Parking Party may reestablish communications with the Parked Party by answering the ring-back call. If the Parking Party does reestablish communications with the Parked Party, timer T-Arb is stopped. If T-Arb exp
30、ires before the Parking Party answers the ring-back call, or if the call is rejected by the Parking Party, and timer T-Rbt has not expired three times, then the call shall be reparked against the Parked DN and timer T-Rbt started. If T-Arb expires and timer T-Rbt has expired three times, the call sh
31、all be cleared or forwarded based on the “Ring-back failure treatment“ subscription option. An in-band indication may be provided to the Parked Party during ring-back (see figure 1, part 3). 4.2.3 Exceptional procedures 4.2.3.1 Activation/deactivation No exceptional procedures for activation or deac
32、tivation have been identified. 4.2.3.2 Invocation and operation The following list identifies the exceptional procedures for the invocation and operation of the Call Park service: Call Park request: If any of the following actions are taken by the Parking Party, the network shall provide an indicati
33、on to the Parking Party giving the reason for failure (see figure 1, part 1): Call Park is attempted, but there is no call in the active (i.e., talking) state; Call Park is attempted, but the Parked DN is not valid (for example, it is not properly formatted, is not in service, vacant code, is not a
34、number in the served users local exchange, etc.); Call Park is attempted, but the Parked DN and Parking DN are not in the same Call Park Subscriber Group; Call Park is attempted, but there is already a call parked against the Parked DN. ATIS-1000653.1996 6 Call Park Retrieve request: If any of the f
35、ollowing actions are taken by the Call Park Retrieving party, the network shall provide an indication to the user giving the reason for failure (see figure 1, part 2): Call Park Retrieve is attempted, but the user is not subscribed to the service; Call Park Retrieve is attempted, but the Parked DN i
36、s not valid (for example, it is not properly formatted, is not in service, vacant code, is not a number in the served users local exchange, etc.); Call Park Retrieve is attempted, but the Parked DN and Retrieving DN are not in the same Call Park Subscriber Group; Call Park Retrieve is attempted, but
37、 there is no call parked against the Parked DN. Ring-back After Time-out: No exceptional procedures for Ring-back After Time-out have been identified. 4.2.4 Alternative procedures No alternative procedures have been identified. 4.3 Interworking considerations The operation of this service is not aff
38、ected by the nature (ISDN or non-ISDN) of the far end of the connection. 4.4 Network capabilities for charging It shall be possible for the service provider to charge accurately for this service. 4.5 Interactions with other supplementary services 4.5.1 Call Waiting If a Call Waiting indication is re
39、ceived during an active call, the active call may be parked so that the Call Waiting call may be answered. The network shall allow Call Waiting to be used to reoffer a parked call when timer T-Rbt expires (i.e., during ring-back). 4.5.2 Call Hold The network shall not allow a call that has been put
40、on Hold to be parked until it has been retrieved from the Held state and is again active. 4.5.3 Multi-Level Precedence and Preemption There are no interactions between Call Park and Multi-Level Precedence and Preemption (MLPP), as defined in ANSI T1.619. The Parked Party is still considered active a
41、t their serving exchange while the call is parked, and so normal MLPP procedures apply to the Parked Party. 4.5.4 User-to-User Signaling There are no interactions between Call Park and User-to-User Signaling, as defined in ANSI T1.621. 4.5.5 Message Waiting Indicator Control and Notification There a
42、re no interactions between Call Park and Message Waiting Indicator Control and Notification, as defined in ANSI T1.622. 4.5.6 Calling Line Identification Presentation If Calling Line information was delivered during call establishment, the network shall save the information and redeliver it during R
43、ing-back After Time-out, following the procedures defined in ANSI T1.625 for presenting the information. The network may also deliver this information during Call Park Retrieve. 4.5.7 Calling Line Identification Restriction ATIS-1000653.1996 7 If Calling Line Identification Restriction applied when
44、the call was originally established, then the same restriction shall apply if the network redelivers the information during Call Park Retrieve or Ring-back After Time-out, following the procedures defined in ANSI T1.625 for presenting the information. 4.5.8 Routing, Bridging, and Transfer of Emergen
45、cy Service Calls (RBTESC) There are no interactions between Call Park and RBTESC, as defined in ANSI T1.628. 4.5.9 Normal Call Transfer There are no interactions between Call Park and Normal Call Transfer, as defined in ANSI T1.632. A parked call is not present at any users terminal, and so is not a
46、vailable for transfer. The network shall not allow a ring-back call termination to be transferred until after the call has been answered. 4.5.10 Calling Name Identification Restriction If Calling Name Identification Restriction applied when the call was originally established, then the same restrict
47、ion shall apply if the network redelivers the name information during Call Park Retrieve or Ring-back After Time-out, following the procedures defined in ANSI T1.639 for presenting the name information. 4.5.11 Calling Name Identification Presentation If Calling Name information was delivered during
48、call establishment, the network shall save the information and redeliver it during Ring-back After Time-out, following the procedures defined in ANSI T1.641 for presenting the information. The network may also deliver this information during Call Park Retrieve. 4.5.12 Call Deflection If a parked cal
49、l is retrieved or answered during Ring-back After Time-out, and was originally an incoming call, the network shall allow the call to be deflected as defined in ANSI T1.642. The network shall not allow a ring-back call termination to be deflected until after it has been answered. 4.5.13 Explicit Call Transfer There are no interactions between Call Park and Explicit Call Transfer, as defined in ANSI T1.643. A parked call is not present at any users terminal, and so is not available for transfer. The network shall no
