Telephonic communications – Centralized switching system – Class of service determination or transmission
Reexamination Certificate
2001-11-30
2004-10-19
Matar, Ahmad F. (Department: 2642)
Telephonic communications
Centralized switching system
Class of service determination or transmission
C379S244000
Reexamination Certificate
active
06807273
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates generally to the field of telecommunications, particularly to digital switching systems used to route calls within telecommunication networks, and more particularly to a method for bypassing the common control and switch matrix of a digital switching system.
BACKGROUND
A class 5 central office comprises a building or room which houses a class 5 switching system, which operates to connect telephones and other devices used by end-user customers (“subscribers”) to a telecommunications network such as the public switched telephone network (“PSTN”). A class 5 digital switch also converts the analog signals used by telephones, modems, FAX machines, and some PBX trunks, into the digital signals that are routed through a digital telecommunications network. The class 5 digital switch also provides special services for caller ID displays and message waiting lights for subscribers, and it processes and routes calls from digital PBX trunks, ISDN lines, and digital loop carriers (“DLC”) to a telecommunications network.
The class 5 central office houses substantial amounts of both equipment and cabling that is designed for a service life measured in decades, because it is extremely difficult and expensive to undertake replacement. To illustrate the physical magnitude of the equipment and cabling, consider that for each telephone line connected directly to the class 5 switch, a pair of copper wires is routed from a subscriber's premises to the class 5 central office. Large installations have hundreds of thousands of such pairs of wires that must be organized, physically supported, and accessible for maintenance. Cables with hundreds of such pairs of wire typically enter the class 5 central office through an underground cable vault. The individual pairs of wire leave the cables and run along a main distribution frame (“MDF”), which provides connection points for test access and connecting to the switching system. The MDF in a large office may be hundreds of feet long to provide many thousands of necessary connection points. Other cables are routed from the connection points of the MDF to line/trunk frames in the class 5 digital switch, which contain the electronics to terminate each telephone line, convert analog signals to digital signals, monitor each line for on-hook and off-hook conditions, dialing, etc. In a similar fashion, other cables are routed from the line/trunk frames, through the MDF or other distribution frame, out of the class 5 office and to the interexchange and long distance networks, where calls are carried from one class 5 switch to another. There may a hundred or more line/trunk frames in a large office, representing an investment of millions of dollars.
Most of the physical plant of the class 5 central office consists of wire, distribution frames, and line/trunk frames. A much smaller portion of the physical plant is devoted to a switch matrix and a common control system. The switch matrix routes calls from one line to another line or trunk, depending on whether the call is to a number in the same central office or a different central office. The common control comprises, among other things, a stored program control system (“SPCS”), which performs call processing, manages the hardware and software of the switch matrix and the line/trunk frames, and manages various communications interfaces to external software systems such as for billing, surveillance, maintenance, and provisioning.
As mentioned previously, the class 5 switching system and its associated cable plant are physically large, expensive, and engineered to remain in service for decades. As mentioned before, replacing such a switching systems is extremely difficult and cost-prohibitive. For these reasons, most subscribers are connected to switching systems that were originally designed years ago, before the deregulation of telecommunications that has taken place around the world. Therefore, they are referred to as “legacy” switching systems.
The deregulation of telecommunications and the rise of the internet have engendered a number of important trends. One trend is the mergers and acquisitions between telephone companies, which leads to the problem of consolidating different networks. While the trunks that carry digital voice and data are inherently compatible with industry standards, consolidating the disparate billing, provisioning, and maintenance software systems that communicate with the SPCS of each class 5 digital switch has proven difficult and expensive. Furthermore, the hardware and software of switching systems are proprietary to each particular manufacturer; therefore, the presence of more than one vendor's switching equipment make it difficult to eliminate redundant costs in the consolidated network. For example, periodic software updates must be purchased for the SPCS of each brand of switching system in the consolidated carrier's network.
Another trend is competition. Competing telephone services, offered by cable television operators, electric utilities, and other competitive providers, often use switching equipment of much newer design that enables the competitive provider to more easily create diverse service packages to offer to customers of traditional telephone companies. The class 5 digital switches owned by incumbent telephone companies were designed for the era of the monopoly telephone company. Consequently, their stored program control systems are not very flexible. The incumbent telephone company is therefore not able to easily create new service packages, but must often wait for years for new features to be added to proprietary software by the manufacturer of the legacy class 5 switching system.
Another trend is toward networks that carry both voice calls and data over common transport based on connectionless access protocols such as asynchronous transfer mode (“ATM”) and transport control protocol/internet protocol (“TCP/IP”), also referred to as “packet networks”. Packet networks simplify the problem of carrying voice and data from region to region. Furthermore, routing calls over such a network permits the use of common routing hardware controlled by so-called “soft switches”, which are not much more than computers running specialized software. “Media gateways”are packet switches that also convert the digital format of voice calls on trunks from legacy class 5 switches into the formats used in packet networks. However, merging traditional class 5 digital switches into a converged network poses problems similar to those of merging networks of different equipment, such as different maintenance, provisioning, and billing software systems. Furthermore, external software systems are necessary to convert the protocols used for setting up calls across ATM and TCP/IP networks back to the corresponding protocol used by the stored program control systems of legacy class 5 switches. Moreover, subscribers are still connected through the legacy class 5 switch, and therefore the services and features available are limited to what is available in the SPCS of the legacy switch.
Another trend is the growth of modem calls, mainly for internet access. Legacy class 5 digital switches were designed for an average call duration of approximately three minutes. The capacities of the switch matrix and the interexchange trunks were engineered by this standard. In other words, the switch matrix and the interexchange trunks can handle simultaneous calls to or from a certain fraction of the attached lines, that fraction having first been determined before the internet. With large numbers of internet modem calls that average 30 minutes or longer, these capacities are being strained. Expanding the trunk and matrix capacities of a legacy class 5 switch is very expensive.
In addition, the long service life of legacy class 5 digital switches is causing problems of maintenance. As the older legacy equipment ages, it is increasingly difficult to find technicians sufficiently knowledgeable to maintain the legacy equipment, and spare parts are bec
Diaz Michael L.
Matar Ahmad F.
Nguyen Quynh H.
LandOfFree
Method and apparatus for bypassing the common control and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for bypassing the common control and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for bypassing the common control and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3312617