Method of arbitrating type II/type III CPE's during SCWID

Details Method of arbitrating type II/type III CPE's during SCWID Method of arbitrating type II/type III CPE's during SCWID

1997-11-14

2001-09-25

Matar, Ahmad F. (Department: 2642)

Telephonic communications

Call or terminal access alarm or control

At substation

C379S171000, C379S177000, C379S215010

Reexamination Certificate

active

06295348

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to telephone equipment at a subscriber end of a subscriber loop, responsive to caller alert signals by transmitting an acknowledgement signal indicative of whether or not a telephone of a particular type is off hook at the subscriber's premises.
BACKGROUND OF THE INVENTION
At subscriber's premises where more than one telephone may be offhook, such telephones may be of different types. Such different types of telephones may be capable of responding to SCWID information and others may not. Furthermore, some telephones may be capable of sending acknowledgement signals back to a telephone switch whereas others may not. In addition, some telephones are capable of extended service such as ADSI service and an indication must be provided to the switch as to whether or not an ADSI compliant telephone is connected to the subscriber line.
Telephone companies and the telephone industry have expressed a desire to always allow the highest level of service. This means that it is not acceptable to reduce to the lowest common denominator and not allow ADSI events to occur if multiple sets are offhook at the subscriber premises. In essence, it is desirable never to block ADSI events as this is a high value user pay service.
It would be desirable to send different acknowledgment signals, to indicate the presence or absence of offhook telephones of particular types on the subscriber loop.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, there is provided an method of signalling a telephone switch to indicate the presence of a telephone of a pre-defined type on a subscriber loop. The method includes the steps of:
a) sensing the subscriber loop to detect whether or not a telephone of a pre-defined type is connected to the subscriber loop; and
b) transmitting to the telephone switch a first acknowledgement signal if the telephone of the pre-defined type is connected to the subscriber loop and off-hook and transmitting to the telephone switch a second acknowledgement signal if the telephone of the pre-defined type is not off-hook.
Preferably, the method includes the step of detecting low frequency modulation on the subscriber loop, to detect whether or not the telephone of the pre-defined type is off-hook.
Preferably, the method includes the step of monitoring dc voltage or dc current on the subscriber loop to detect signal transitions indicative of an extension-in-use.
Preferably, the method includes the step of determining whether or not a signal transition indicative of an extension-in-use occurs within a pre-defined window of time.
Preferably, the method includes the step of determining whether or not a signal transition indicative of an extension-in-use occurs within first or second pre-defined windows of time.
Preferably, the method includes the step of transmitting the first acknowledgement signal if the signal transition indicative of an extension-in-use occurs within the first window of time and transmitting the second acknowledgement signal if the signal transition indicative of an extension-in-use occurs within the second window of time.
Preferably, the method includes the step of detecting a CAS signal on the subscriber loop and starting a timer in response to detection of the CAS signal.
Preferably, the method includes the step of defining a pre-ack delay period as a pre-defined period of time measured from detection of the CAS signal, the first and second windows of time falling within the pre-ack delay period.
Preferably, the method includes the step of determining whether or not a signal transition indicative of an extension-in-use occurs within a first or second half of the pre-ack delay period.
Preferably, the method includes the step of transmitting the first acknowledgement signal if the signal transition indicative of an extension-in-use occurs within the first half of the pre-ack delay period and transmitting the second acknowledgement signal if the signal transition indicative of an extension-in-use occurs within the second half of the pre-ack delay period.
Preferably, the method includes the step of disabling the transmission of the acknowledgement signal, and receiving FSK data from the subscriber loop when an ADSI detect flag is set active.
Preferably, the method includes the step of transmitting the acknowledgement signal includes transmitting a DTMF A after a pre-ack delay period from receipt of the CAS signal.
Preferably, the method includes the step of transmitting the acknowledgement signal includes transmitting a DTMF D after a pre-ack delay period from receipt of the CAS signal.
Preferably, the method includes the step of determining whether or not an extension is in use for a period of time less than or equal to the pre-ack delay period from receipt of the CAS signal and if so, setting an ADSI detect flag active according to whether or not the time elapsed since the CAS signal was detected is greater than the pre-ack delay period.
Preferably, the method includes the step of disabling the transmission of the acknowledgement signal when the ADSI detect flag is set active.
Preferably, the method includes the step of setting an ADSI detect flag active according to whether or not the time elapsed since the CAS signal was detected is greater than one-half of the pre-ack delay period.
Preferably, the method includes the step of transmitting the acknowledgement signal after the pre-ack delay period.
Preferably, the method includes the step of disabling the transmission of the acknowledgement signal when an ADSI detect flag is set active.
Preferably, the method includes the step of placing the subscriber loop in an on-hook state for a for a time period equal to one-half of a pre-ack delay time period from receipt of the CAS signal.
Preferably, the method includes the step of muting a receive path until FSK data is received.
Preferably, the method includes the step of waiting a period of time equal to the sum of one-half of the pre-ack delay period and an ack length period from receipt of the CAS signal prior to placing the subscriber loop in an off hook state.
In accordance with another aspect of the invention, there is provided an apparatus for signalling a telephone switch to indicate the presence of a telephone of a pre-defined type on a subscriber loop. The apparatus includes a sensor for sensing the subscriber loop to detect whether or not a telephone of a pre-defined type is connected to the subscriber loop. The apparatus further includes a transmitter for transmitting to the telephone switch a first acknowledgement signal if the telephone of the pre-defined type is connected to the subscriber loop and off-hook and transmitting to the telephone switch a second acknowledgement signal if the telephone of the pre-defined type is not off-hook.
Preferably, the sensor is operable to sense low frequency modulation on the subscriber loop, to detect whether or not the telephone of the pre-defined type is off-hook.
Preferably, the apparatus includes an analog to digital converter for monitoring the voltage or dc current on the subscriber loop to detect signal transitions indicative of an extension-in-use.
Preferably, the apparatus includes a processor for determining whether or not a signal transition indicative of an extension-in-use occurs within a pre-defined window of time.
Preferably, the apparatus includes a processor for determining whether or not a signal transition indicative of an extension-in-use occurs within first or second pre-defined windows of time.
Preferably, the transmitter is operable to transmit the first acknowledgement signal if the signal transition indicative of an extension-in-use occurs within the first window of time and transmit the second acknowledgement signal if the signal transition indicative of an extension-in-use occurs within the second window of time.
Preferably, the apparatus includes a CAS signal detector for detecting a CAS signal on the subscriber loop and a timer started in response to detection of the CAS signal.
Preferably, the apparatus includes a micropr

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