Telephonic communications – Diagnostic testing – malfunction indication – or electrical... – Testing of subscriber loop or terminal
Reexamination Certificate
1999-08-16
2001-08-07
Kuntz, Curtis (Department: 2643)
Telephonic communications
Diagnostic testing, malfunction indication, or electrical...
Testing of subscriber loop or terminal
C379S001040, C379S009000, C379S015050, C379S029010, C379S032010
Reexamination Certificate
active
06272209
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for provision of lifeline telephony for a Voice over Digital Subscriber Line and a system incorporating the same.
BACKGROUND TO THE INVENTION
Digital Subscriber Line (DSL) modem technology has enabled the transmission of digital information at duplex rates from 144 Kbits/s to greater than 1 Mbits/s over the subscriber loop. The demand for additional telephone lines and integrated telephony and data services has given rise to Voice over DSL (VoDSL) solutions. For example a VoDSL system may provide 4 voice channels carried within the digital data over a single twisted pair subscriber loop from a Line Terminating Equipment (LTE) located in the Central Office to a Customer Premises Equipment (CPE). In one implementation, a VoDSL system carries the voice channel(s) in band as encoded data within the data stream and therefore there is no baseband POTS (Plain Old Telephony Service) as would be the case with for example ADSL or G.Lite. Unlike normal telephony the derived voice method of VoDSL requires local power at the CPE to perform the modulation and demodulation.
Conventional analogue POTS telephony over a twisted pair to the LTE has the benefit that during power failure at the customer premises emergency calls can still be placed since the line and the handset at the customer premises are powered from the central office. A disadvantage of existing VoDSL modems is that the amount of power required for normal operation could severely limit the operational loop length if power is fed from the central office and thereby not provide a service able to reach the majority of consumers. This has limited deployment of VoDSL systems to subscribers having an additional conventional POTS line which can be used in the event of power failure. Absence of support for lifeline services has therefore severely hindered deployment into the small business and especially the residential market.
Power feed from LTE has been tried for Integrated Services Digital Network (ISDN) but it requires very high battery voltages and severely limits the operational loop length.
Use of batteries at the CPE to provide backup power in the event of power failure presents other problems. Batteries may be bulky and therefore unattractive to subscribers. Batteries require periodic maintenance to ensure reliability; and battery faults may not be detected until a local power failure occurs and they then fail to provide power to the CPE and hence provide lifeline support, thus defeating the object of their presence in the system.
OBJECT OF THE INVENTION
The invention seeks to provide an improved method and apparatus whereby to provide a voice lifeline service for a Voice over DSL system.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided a method of operating customer premises equipment for a voice over digital subscriber loop (VoDSL) system comprising at least one local telephony port and a subscriber loop port, the method comprising the steps of:
connecting said at least one local telephony port directly to said subscriber loop port responsive to detection of a customer premises equipment power supply failure;
whereby to enable direct communication between said at least one local telephony port and said subscriber loop port so as to maintain at least a voice service to the customer.
Advantageously, the method allows lifeline voice service to be provided by a LTE VoDSL modem arrangement.
Advantageously, upon loss of VoDSL capability to the CPE, lifeline voice service operation is achieved by an automatic change of the method of transmitting voice from VoDSL to POTS. To provide lifeline service the LTE modem is automatically reconfigured from a VoDSL modem to a POTS subscriber line interface.
Advantageously, when the LTE re-establishes VoDSL capability with the CPE, the LTE is automatically reconfigured from a POTS Subscriber line interface to a VoDSL modem.
Advantageously, the LTE will interwork with any standard POTS device.
Advantageously, the LTE is capable of being reconfigured so as to emulate a POTS line card or an analogue or ISDN modem.
Advantageously, the CPE modem may be disconnected or removed and lifeline calls to be made by connection of a POTS device to the subscriber's port.
According to another aspect of the invention, there is provided a method of operating line terminating equipment for a voice-over digital subscriber loop comprising a subscriber loop port, and comprising the steps of:
sending and receiving digital subscriber loop signals via said subscriber loop port;
receiving an indication at said subscriber loop port of a change of operational mode of customer premises equipment connected to said subscriber loop port from a digital subscriber loop to analogue POTS loop;
operating said line termination equipment in an analogue POTS mode responsive to receipt of said indication.
The invention is also directed to a method by which the described apparatus operates and including method steps for carrying out every function of the apparatus.
According to another aspect of the invention, there is provided a line terminating equipment comprising a subscriber loop port and a network connection port; a voice-over digital subscriber loop modem circuit; and a direct electrical connection circuit; the equipment being arranged to operate in a first mode wherein a telecommunications connection is maintained between said subscriber loop port and said network connection port via said voice-over digital subscriber loop modem, and in a second mode wherein a telecommunications connection is formed between said subscriber loop port and said network connection port via said direct electrical connection.
According to a further aspect of the invention, there is provided a customer premises equipment comprising a subscriber loop port and at least one local telephony port; a voice-over digital subscriber loop modem circuit; and a direct electrical connection circuit; the equipment being arranged to operate in a first mode wherein a telecommunications connection is maintained between said subscriber loop port and said at least one local telephony port via said voice-over digital subscriber loop modem, and in a second mode wherein a telecommunications connection is formed between said subscriber loop port and said local telephony port via said direct electrical connection.
The invention also provides for a system for the purposes of digital signal processing which comprises one or more instances of apparatus embodying the present invention, together with other additional apparatus.
The preferred features may be combined as appropriate, as would be apparent to a skilled person, and may be combined with any of the aspects of the invention.
REFERENCES:
patent: 5142571 (1992-08-01), Suzuki et al.
patent: 5216704 (1993-06-01), Williams et al.
patent: 5220597 (1993-06-01), Horiuchi
patent: 5305377 (1994-04-01), D'Arcy et al.
patent: 5483574 (1996-01-01), Yuyama
patent: 5581612 (1996-12-01), Nishikawa
patent: 5883941 (1999-03-01), Akers
patent: 5889856 (1999-03-01), O'Toole et al.
patent: 5912957 (1999-06-01), Park
patent: 6088362 (2000-07-01), Turnbull et al.
patent: 6141330 (2000-10-01), Akers
patent: 6141356 (2000-10-01), Borman
patent: 2 313 979 (1997-12-01), None
Bridger Mark
Farrington Jeffrey
Grant Michael F
Tate Christopher
Wallace Andrew D
Kuntz Curtis
Lee, Mann, Smith McWilliams, Sweeney and Ohlson
Nortel Networks Limited
Tieu Binh K.
LandOfFree
Lifeline telephony provision for voice over digital... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lifeline telephony provision for voice over digital..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lifeline telephony provision for voice over digital... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2505357