Title: Architecture for providing flexible, programmable supplementary services in an expandable telecommunications system
Abstract: This invention relates to a supplementary services layer (SSL) application in the switching node for the development and execution of subscriber-based supplementary services. The SSL communicates with the L4 application through an L4-L5 interface. Therefore, a system operator may configure the switching node to execute supplementary services without intervention from a host application and without modification to the current L4 application. The SSL also communicates with the L5 application in order for that application to integrate supplementary services without further modifications. The SSL comprises a Database Interface Service, a Service Object Manager (SOM) and one or more instances of a Supplementary Service Object (SSO). The database interface service provides connection to an external database which stores each subscriber's profile. Each SSO instance implements one or more supplementary services for a call. The SOM exercises overall control over these SSO instances.
Patent Number: 6,898,199 Issued on 05/24/2005 to Silva, et al.
| Inventors:
|
Silva; Michael C. (Centerville, MA);
Hebert; Mark P. (Kingston, MA)
|
| Assignee:
|
Excel Switching Corporation (Hyannis, MA)
|
| Appl. No.:
|
272636 |
| Filed:
|
March 18, 1999 |
| Current U.S. Class: |
370/352; 370/392; 370/401; 370/463; 379/201.01 |
| Intern'l Class: |
H04L 012/56; H04Q011/08 |
| Field of Search: |
370/259,260,359,360,386,400,401,410,903,352,375,389,392,469
379/201.01,272,230,909,273,335,900.1,930.7
|
References Cited [Referenced By]
U.S. Patent Documents
| 5544163 | Aug., 1996 | Madonna.
| |
| 5657451 | Aug., 1997 | Khello.
| |
| 6058181 | May., 2000 | Hebert.
| |
| 6088749 | Jul., 2000 | Hebert et al.
| |
| Foreign Patent Documents |
| 0 849 960 | Jun., 1998 | EP.
| |
| 0849960 | Jun., 1998 | EP.
| |
| 9903251 | Jan., 1999 | WO.
| |
| 99 03251 | Jan., 1999 | WO.
| |
| 00 23898 | Apr., 2000 | WO.
| |
Other References
Bellcore, Generic Requirements, "Call Processing," GR-505-CORE, Issue 1, Dec., 1997.
|
Primary Examiner: Qureshi; Afsar
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This invention is related to the following copending U.S. Patent Applications:
- U.S. Pat. No. 6,370,136 titled, DIALING PLAN ARRANGEMENT FOR EXPANDING
TELECOMMUNICATIONS SYSTEM; and
- U.S. Pat. No. 6,526,050 titled, PROGRAMMING-CALL-PROCESSING APPLICATION
IN A SWITCHING SYSTEM, each of which was filed on even date herewith and assigned
to the assignee of the present invention.
Claims
1. A switching system comprising:
A) a plurality of switching nodes each of which contains:
1. a programmable switch that includes a software protocol application that manages
calls in that particular switching node, and that performs call-processing operations
defined by a system operator;
2. a plurality of line cards with ports for connections between the system and
one or more external networks, said line cards including a line card software protocol
application that manages calls in the line card, and that exchanges data between
the switching system and one of said external networks; and
3. a supplementary services application for the development and execution of
supplementary services for each call processed in the switching system;
B) an internodal switching network interconnecting each of the plurality of switching
nodes for conveying switched telecommunications data between them;
C) a host computer that includes a software protocol application that manages
calls in the host, and which host software protocol application exercises supervisory
control over the plurality of switching nodes;
D) a host network linking the host computer and the switching nodes for supervisory
and informational communications; and
E) host-switch interface means for communicating and passing information between:
1. the software protocol application that manages calls in a switching node,
and the supplementary services application, and
2. the host software protocol application, and the supplementary services application.
2. The switching system of claim 1 wherein the supplementary services application comprises:
A) a database interface service for connection to an external database which
stores subscriber's profiles for each call processed in the switching system;
B) at least one instance of a supplementary service object for implementing supplementary
services identified in the subscriber's profile; and
C) a service object manager which exercises overall control over the supplementary
service object instances.
3. The switching system of claim 2 wherein the line cards provide connections
to subscribers and the external database stores a subscriber profile for each subscriber
and each external network.
4. The switching system of claim 3 wherein each instance of the supplementary
services object comprises:
A) at least one service element object which implements a supplementary service;
B) an associate party manager object which interfaces with other instances of
the supplementary services object;
C) a service control object for managing other objects in the supplementary services
object instance and serving as the interface between these objects and the software
protocol application that manages calls in the switching nodes;
D) support services objects for providing the functions needed by the service
element object, the associate party manager object, and the service control object
to perform their respective tasks; and
E) control services objects that implement control models for allocating, de-allocating
and addressing the service element object and the associate party manager object.
5. The switching system of claim 4 wherein the supplementary services application
further comprises:
A) a time slot table for associating time slots for a call with a trunk group;
B) a trunk group table for obtaining information about trunk group's properties;
C) a profile table for obtaining records with subscribers profiles; and
D) means for associating a record in the profile table with the trunk group.
6. The switching system of claim 5 wherein the trunk group table comprises profile
identifiers for trunk groups associated with external networks, the profile identifiers
are associated with records in the profile table.
7. The switching system of claim 6 wherein the supplementary services application
creates and executes an instance of the supplementary service object that corresponds
with the subscriber profile records.
8. The switching system of claim 7 wherein the supplementary services application
and the host application communicate with the application that manages calls in
the switching nodes through the same interface.
9. A method for developing and executing supplementary services in a switching
system which comprises a plurality of switching nodes that each include a software
protocol application for managing calls in that particular switching node, and
line cards with associated ports, and a line card software protocol application
for exchanging messages between the line cards of the switching system and external
networks and/or subscribers served by the associated ports, an internodal network
interconnecting the switching nodes, at least one host computer for running a supervisory
software application, a host network linking each host computer with the switching
nodes, a supplementary services application in each switching node, the supplementary
services application implementing supplementary services for calls processed on
the system, said method comprising the steps of:
A) transmitting a call from one of said associated ports through the line card
software protocol application running on the line card with which that port is
associated, to a software protocol application that manages calls in the switching
node on a given switching node having the supplementary services application;
B) mapping time slots for the call to a trunk group by using a time slot table;
C) identifying the trunk group type by using a trunk group table;
D) obtaining a profile identifier for the trunk group;
E) associating the profile identifier with a profile record in a profile table;
and
F) creating and executing an instance of a supplementary service object that
corresponds with that profile record.
10. The method of claim 9 wherein the step of identifying further comprises the
step of checking the trunk group type to determine whether the port is a subscriber port.
11. The method of claim 10 wherein the step of obtaining comprises the steps of
1. accessing an external database for the profile identifiers for trunk groups
associated with subscriber ports, and
2. retrieving the profile identifiers from the trunk group for ports associated
with external networks.
12. A switching node, comprising:
(A) a programmable software protocol application for managing calls in the switching
node, the software protocol application communicable with an associated host software
protocol application running on an associated host device that exercises supervisory
control over the switching node; and
(B) a supplementary services application for the development and execution of
supplementary services for calls processed in the switching node, including a supplementary
services interface means for passing information between said supplementary services
application and the software protocol application for managing calls in the switching
node.
13. The switching node as defined in claim 12 further comprising,
said programmable software protocol application for managing calls in the switching
node including interface means for communicating with line card software protocol
applications ruing on associated line cards for connections between the switching
node and one or more external networks.
14. The switching node as defined in claim 12 wherein said supplementary services
application further comprises,
(A) at least one instance of a supplementary service object; and
(B) a service object manager which exercises control over said supplementary
service object.
15. The switching node as defined in claim 14 wherein each instance of the supplementary
services object comprises:
at least one service element object which implements a supplementary service.
16. The switching node as defined in claim 14 wherein each instance of the supplementary
services object comprises:
an associate party manager object which interfaces with other instances of the
supplementary services object.
17. The switching node as defined in claim 14 wherein each instance of the supplementary
services object comprises:
a service control object for managing other objects in the supplementary services
object instance and serving as the interface between these objects and the application
that manages calls in the switching node.
18. The switching node as defined in claim 14 wherein each instance of the supplementary
services object comprises:
a support services object for providing the functions for any of the following:
the service element object, an associate party manager object, and a service control
object to perform their respective tasks.
19. The switching node as defined in claim 14 wherein each instance of the supplementary
services object comprises:
a control services object that implements control models for allocating, de-allocating
and addressing a service element object and an associate party manager object.
20. The switching node as defined in claim 12 wherein said supplementary services
application further comprises:
a database interface service for connection to an external database which stores
subscriber profiles for calls processed in the switching node, and
at least one instance of a supplementary service object for implementing supplementary
services identified in the subscriber's profile.
21. The switching node as defined in claim 12 wherein said supplementary services
application and the host application communicate with the application that manages
calls in the switching node through the same interface.
Description
TECHNICAL FIELD
The invention relates generally to the field of telecommunications switching
systems and more particularly to a software application in a switching node that
enables the switching node to implement subscriber-based services without supervision
from a host application.
BACKGROUND OF THE INVENTION
An example of a switching system to which the present invention applies is described
in U.S. Pat. No. 5,544,163, Expandable Telecommunications System, the contents
of which are incorporated by reference herein. A telecommunication switching node
described therein has line cards with multiple ports connected to subscriber's
telephone lines or to other devices such as PSTN trunks. The switching node also
includes a switch/matrix card and at least two system buses for switching calls
received on one port to another port in the system. One of these buses is an incoming
bus that passes messages from the line cards to the matrix card and the other is
an outgoing bus which transmits messages from the matrix card to the line cards.
In order to perform switching on calls, the switching node receives information
from and transmits information to line card ports over the system buses at predetermined
times known as time slots. Each time slot generally corresponds with a port on
the switch. The time slots associated with each port and the software applications
that manage calls on those time slots are generally termed "channels".
Each call involves connection between two ports. Because communication between
these ports is bi-directional, it thus requires four time slots on the system buses.
One time slot is used for transmission from one port to the matrix card, a second
time slot is used for retrieving information from matrix card and sending it to
the other port; the other two time slots are used for transmissions in the other direction.
The telecommunications system also includes a host, i.e., a group of software
applications that typically reside on a computer dedicated to those applications.
The switching nodes on the system are interconnected by an internodal switching
network. A second network termed the "host network," interconnects the switching
nodes and the host computer for supervisory control. The host, the switching nodes
and the line cards each includes a software protocol application that processes
calls at its level of the system. Specifically, a Layer 5 (L5) protocol application
in the host manages calls at the host level; a Layer 4 protocol application (L4)
in the switch manages calls at the switch level; and Layer 3 (L3) protocol applications
in the line cards handle calls at the line card level of the system.
Traditionally, the L5 application in the host also managed the L4
functions in the switch. All requests from the L3 application to the L4 application
were transmitted to the L5 application and the L5 application instructed the L4
application on how the handle each request. Since the L5 application was involved
in directing nearly all real-time call processing on the switch, the message traffic
between the switch and the host was high and this sometimes delayed the transmission
of messages between the host and the switch. Moreover, if the host-to-switch link
failed or if the host failed, the switch was basically rendered inoperable.
This problem was largely resolved by expanding the L4 application in the switch
to provide functions previously performed exclusively in the L5 application. The
expanded L4 application is a open and programmable layer that provides services
such as, channel management, connection management, tone and announcement services
and conference services. Channel management enables the L4 application to recognize
incoming calls, answer calls, and release calls; connection management provides
the ability to disconnect two channels, tone and announcement services provide
the ability to play and receive tones and play announcements; and conference services
provide the ability to connect multiple parties during a call. With the expanded
L4 application, a system owner/operator might expand pre-defined L4 call management
operations to accommodate unique call processing requirements. Thus, host applications
may be simplified, or in some cases totally eliminated.
Each call on a time slot is associated with a subscriber profile which identifies
the supplementary services available to that call. Examples of supplementary services
include call waiting, call forwarding and conference calling among others. Applications
that process these supplementary services reside in the host. Thus, when a call
is received on one time slot from the L3 application, the L4 application transmits
a request to the L5 application in order to identify the appropriate subscriber
profile and supplementary services for that call. The L5 application locates the
subscriber profile associated with the call, controls the supplementary services
identified in the subscriber profile and returns the appropriate results to the
L4 application. The L4 application then performs switching functions on the call.
Since the switch still relies on the host to identify and process supplementary
services, a host failure prevents the switching node from properly processing calls
with supplementary services.
Moreover, when a supplementary service is added or modified, the L5 application
must be updated. This increases the risk of introducing errors to the L5 application
which may adversely affect the processing of supplementary services or other L5 functions.
SUMMARY OF THE INVENTION
We have created a supplementary services layer (SSL) application in the switching
node for the development and execution of subscriber-based supplementary services.
The SSL communicates with the L4 application through an L4-L5 interface in order
for the SSL to obtain access to services offered by the L4 application. Therefore,
a system operator may configure the switching node to execute supplementary services
without intervention from a host application and without modification of the current
L4 application. The SSL also communicates with the L5 application in order for
that application to integrate supplementary services without further modifications.
With this arrangement, the supplementary services functions are separated from
the L5 application and transferred to the switching node. This makes it easier
for the system owner to add or modify supplementary services.
Specifically in the preferred embodiment of the invention, the SSL comprises
a. Database Interface service, a Service Object Manager (SOM) and one or more instance
of a Supplementary Service Object (SSO). The database interface service provides
connection to an external database which stores each subscriber's services profile.
Each SSO instance implements one or more supplementary services for a call. The
SOM exercises overall control over these SSO instances. It allocates, de-allocates,
initializes, addresses, and supports SSO instances. Each SSO instance further comprises
a Service Control object (SC), one or more Service Element objects (SE), an Associate
Party Manager object (APM), Support Services objects, and Control Services objects.
The SC activates the other objects in an SSO instance on a per-need basis. It
also prioritizes these objects and manages interaction between them. The SC is
the only object that interfaces with the L4 application; it has access to all of
the L4 services and thus, it passes requests from other objects to the L4 application.
Each SE object implements a single supplementary service and the SE objects are
loosely coupled through the SC. Each SE object defines an interface with the SC
for instructing the SC on how to implement a supplementary service. An instance
of the SE object is created when it is needed to perform a task and it is de-allocated
when the task is completed. The APM serves an interface object to other SSO instances.
The SC, SE, and APM each has its own support services. These support services
provide the functionality needed to perform each task. An example of a support
service is a software object that provides access to an external application. The
SE and APM objects also have control services that implement control models for
allocating, de-allocating and addressing these SE and APM objects. These control
services directly manage multiple instances of the SE and APM state machines and
the control services are indirectly accessed by the SC.
The SSL implements both subscriber and PSTN call models. If a call is from a
subscriber, the SOM creates a subscriber SSO instance and it obtains the list of
supplementary services for that subscriber from the external database. If the call
is from the PSTN, the SOM creates a PSTN SSO instance and it obtains the profile
for the PSTN subscriber from local sources.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention description below refers to the accompanying drawings, of which:
FIG. 1 is a diagram of a call switching system incorporating the invention;
FIG. 2 is a schematic diagram of the SSL and how the objects interact with each
other and with the L5 and L4 protocol applications;
FIG. 3 is a depicts of two SSO instances and the interaction between these instances
and other SSL objects;
FIG. 4 shows the tables used by the SSL and the relationships between these
tables; and
FIG. 5 is a flow diagram of how a incoming call is handled.
DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT
The communications network in FIG. 1 is configured to process calls to, from
and within a switching system
10. The switching system
10 includes
switching nodes
32b-
32f that are connected by a ring-like
internodal switching network
34 to pass among them the various messages
handled by the switching system
10. Each switching node
32b-
32f
is associated with a plurality of network/line interfaces (not shown) which
provide connections between the switching system
10 and subscribers' lines,
for example, and also with other switching systems such as the PSTN. These interfaces
also provide access to system resources such as DSP resources and voice-mail functions.
The communications network also includes a host computer
24 that runs a
protocol application
22. The host computer
24 is linked to the switching
nodes
32b-
32f by a host network
26.
The host computer
24, the switching nodes
32b-
32f
and the line cards (not shown) include software applications which process
calls in these layers. A Layer 5 (L5) protocol application
22 in the host
24 manages calls at the host level; a Layer 4 (L4) protocol application
36b-
36f in each switching node
32b-
32f
manages calls at the switching node level; and a Layer 3 (L3) protocol application
in each line cards manages calls at the line card level. In the present invention,
Supplementary services layer (SSL) applications for executing supplementary services
were also included in each switching node
32b-
32f.
Examples of supplementary services include call waiting, call forwarding, and caller
identification, among others. The SSL enables the system operator/owner to develop
and execute subscriber-based supplementary services in each switching node
32b-
32f
without intervention from a host application
22.
The illustrative SSL
200 shown in FIG. 2 communicates with the L4 application
220 through the existing host-switch interfaces
240 in the switching
nodes
32b-
32f. The SSL
200 comprises a Database
Interface Service
202, a Service Object Manager (SOM)
204 and one
or more instances
206/
208 of a Supplementary Service Object (SSO).
The database interface service
202 provides connection to an external database
(not shown) which stores each subscriber's service profile. Each SSO instance
206/
208
performs the supplementary services needed during a call. The SOM
204 coordinates
the activities of the SSO instances
206/
208 and exercises overall
control over these instances. Specifically it allocates, de-allocate, initializes
and addresses each SSO instance
206/
208.
FIG. 3 is a detailed diagram of two SSO instances
302/
352. Each
SSO instance comprises a Service Control object (SC)
304/
354, one
or more Service Element (SE) objects
306/
356, an Associate Party
Manager object (APM)
308/
358, Support Services objects
314-
318/
364-
368,
and Control Services objects
310-
312/
360-
362. The SC
304/
354 activates each of the other SSO objects in its SSO instance
302/
352 on a per-need basis. It also manages interactions between
other SSO objects and determines the processing priority for these objects. The
SC
304/
354 is the only SSO object that interfaces with the L4 application
340 and it has access to all L4 services; thus, it services requests from
other SSO objects to the L4 application.
Each instance of the SE
306/
356 implements a single supplementary
service for a call and it accesses a suite of standard support services
314/
364
in order to implement the supplementary service. There may a number of different
types of SEs
306/
356 active for a single call. Each SE object implements
a single supplementary service and the SE objects are loosely coupled through the
SC. Each SE object defines an interface with the SC for instructing the SC on how
to implement a supplementary service. An instance of the SE object is created when
it is needed to perform a task and it is de-allocated when the task is completed.
Specifically, even though an SE
306/
356 instance is de-allocated,
the call may still continue and other SE instances
306/
356 may be
instantiated to perform other supplementary services. The APM
308/
358
serves as an interface object to other SSO instances
302/
352. The
instance of APM
308/
358 that initiates a connection with another
SSO instance is the "connection owner." The connection owner initiates and terminates
communications with the L4 application
340 through its SC
304/
454.
Even though multiple APM instances
308/
358 may be connected to the
L4 application
340, the L4 application
340 can only communicate with
one APM
308/
358 at a time. The communicating APM
308/
358
is the ‘active’ APM and all other APMs
308/
358 connected
to the L4 application
340 are ‘held’ APMs. APMs are dynamic
and may be allocated/de-allocated as need arise.
The SCs
304/
354, SEs
306/
356, and APMs
308/
358
each have support services
314-
318/
364-
368. These support
services
314-
318/
364-
368 provide the functionality
needed to perform each task. An example of a support service is a software object
that provides access to external applications such as a Network Protocol Data Intelligence
(NPDI) service
320 and
370 and a Dialing Plan Engine (DPE) Application
322 and
372. The NPDI service translates messages in different network
signaling protocols. The DPE application applies network processing rules to each
call. Network processing rules indicates how calls are processed. The SE
306/
356
and APM
308/
358 also have control services
310-
312/
360-
362
that implement control models for allocating, de-allocating and addressing the
SE
306/
356 and APM
308/
358 objects. Since multiple
instances of the SE
306/
356 and APM
308/
358 may be
active simultaneously, the control services
310-
312/
360-
362
directly manage the SE
306/
356 and APM
308/
358 services.
The control services
310-
312/
360-
362 are accessed by
the SC
304/
354 in order for the SC
304/
354 to manage
the SE and APM
310-
312 and
360-
362 objects.
FIG. 4 shows the SSL tables and the relationships between them. The L4 application
receives calls through a port from the L3 application in a line card. The call
is transmitted on two time slots in the switching node. One time slot is used for
transmission from the L3 application to the L4 application, and the other time
slot is used for retrieving switched data from the L4 application and sending it
to the L3 application at another port. The time slots for each call are mapped
to trunk groups by using a Time slot to Trunk Group Table
502. A trunk group
is a collection of time slots/channels with similar properties. Once a trunk group
identifier is obtained, a trunk group table
504 is used to obtain information
about that trunk group's properties. For example, the trunk group table
504
includes a field that identifies whether associated ports are subscriber ports
or PSTN ports. Based on the types of port, the SSL derives the calling and called
parties' subscriber profiles, which identify the available supplementary services
and ultimately defines which SSO objects may be executed.
For each PSTN trunk group, the trunk group table
504 contains profile
identifiers common to all calls involving subscribers connected to that PSTN. The
PSTN trunk group profile identifier is used by the SSL to obtain a record from
a SSL Profile table
506. For subscribers connected to this system, the SSL
obtains subscriber port profile identifiers from the external database and uses
them to obtain individual records from the SSL Profile Table
506. Based
on the records in the SSL Profile Table
506, the SSL creates the SSO instance
and instantiates appropriate objects in the SSO instance.
FIG. 5 is a flow diagram of an incoming call to a line card. At Step
1,
the L4 application receives a call through a port from the L3 application in the
line card. The L4 application transmits the call to the SSL, which must identify
the trunk groups to which the ports belongs. In Step
2, the SOM maps the
time slots to trunk groups by using the Time Slot To Trunk Group table. In Step
3, the SOM identifies the trunk group types from a Trunk Group Table. In
Step
4, the SOM checks the trunk group types to determine whether the port
is a PSTN port or a subscriber port. If the port is a PSTN port, the SOM obtains
a profile ID from the trunk group in Step
5. If the port is a subscriber
port, the SOM accesses the external database to obtain the profile ID in Step
6.
In Step
7, the SOM maps the profile ID to a record in the SSL profile table.
The record identifies which objects in the SSO instance must be activated. In Step
7, the SOM creates an SSO instance that matches the SSL profile table record.
In Step
8, the SOM invokes the appropriate objects in the SSO instance.
Since the SSL is separated from the L5 application and each object in an SSO
instance performs a specific task, when the processing requirements for the supplementary
services change, the system operator only has to change the SSO object that is
affected by the new processing requirements. For example, the system operator may
modify a supplementary service by changing only the service element object that
implements that service. Moreover, each time a new supplementary service is added,
the system operation may only have to add the service element object that implements
the supplementary service. Since the SE object for each supplemental service defines
its interface with the SC object, the system operator may customized or introduce
new supplementary services without software downloaded from the host and the risk
of introducing processing errors that effects other areas in the L4 application
is greatly reduced.
The foregoing description has been directed to specific embodiments of this invention.
It will be apparent, however, that other variations and modifications may be made
to the described embodiments, with the attainment of some or all of their advantages.
Therefore, it is the object of the appended claims to cover all such variations
and modifications as come within the true spirit and scope of the invention.
*
