Telecommunications – Radiotelephone system – Including private cordless extension system
Reexamination Certificate
1999-05-24
2002-02-05
Bost, Dwayne (Department: 2681)
Telecommunications
Radiotelephone system
Including private cordless extension system
C455S088000, C455S415000, C455S420000
Reexamination Certificate
active
06345187
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to caller identification (CID) technology within a cordless telephone environment. More specifically, it relates to the receipt and display of Type II CID data by multiple cordless telephones within a single household.
2. Description of the Related Art
Cordless telephones have proven to be popular in domestic, business and industrial environments due to the unrestricted freedom of movement they provide users. In fact, in 1997, for the first time ever, sales of cordless telephones exceeded sales of corded telephones with total cordless units sold being in excess of 28 million. Furthermore, total sales for 1998 are expected to have increased over 1997 sales by at least 25 percent.
With a cordless telephone, a telephone subscriber is not confined by the limitation of a station set extension cord. Instead, the subscriber has complete freedom of movement within a radio frequency (RF) link range of up to about 300 m between a stationary base and its cordless portable handset.
Along with the continued growth of cordless telephone sales are the increased umber of conveniences being offered for use on cordless telephones. Among the any such services are caller identification (CID) and call waiting.
CID is a well known feature that allows a telephone user to identify the party making an incoming call before the call is answered. When a telephone call is directed to a customer having the CID service, the central telephone office (CO) transmits a CID message concurrently with the incoming call. Specifically, the CID data is typically transmitted to the recipient between rings of the incoming call. Upon receipt of the CID data, the dialed party may use the CID data to screen his or her incoming calls, keep a journal of incoming calls, monitor for prank calls, or for any other personal or business need.
To enjoy the benefits of conventional CID service, a person typically rents or purchases a special component that receives and displays the CID data. This component may, for example, be a separate box that must be connected in line with a standard telephone unit. Cordless telephone subscribers may take advantage of the CID service by utilizing the special CID box in combination with the cordless base station. Still others, may be in possession of a cordless telephone unit capable of displaying the CID data at the handset itself through an integral CID display. Such units allow both the telephone handset and the CID feature to be mobile, thereby adding to the overall convenience of the telephone.
Call waiting is an equally well known feature, whereby a subscriber is virtually assured that he or she will not miss an incoming telephone call. That is, if the subscriber is currently using the telephone, and another call comes through on the same line, a slight tone will be heard by the subscriber. If the subscriber wishes, the current telephone call may be placed on hold while the subscriber checks to see who is on the other line. This is achieved by momentarily pressing a key on the receiver or by depressing an on-hook button. The subscriber may switch back and forth between calls as often as he or she wishes. Similarly to the CID feature, the call waiting feature has been available on cordless telephones for some time now.
Recently, the above described features of CID and call waiting have been combined to create caller identification on call waiting (CIDCW). CIDCW is often referred to in the art as Type II CID. With Type II CID, instead of simply receiving a slight tone, the subscriber can actually discern who is on the other line when they're already engaged in a telephone conversation by virtue of the received Type II CID information. The subscriber can then make an informed decision about whether to interrupt the on-line caller.
FIG. 1
depicts a block diagram of the “handshaking” required in order to implement the Type II CID feature. First, an initial telephone call between the subscriber
10
and a second party
11
is already in progress. As is known in the art, the call between subscriber
10
and the second party
11
is routed through a central office (CO)
13
via communication links
20
and
21
. The subscriber
10
actually receives the call on subscriber line
35
through telephone line
37
. Next, a third party
12
seeks to place a telephone call directly to the subscriber
10
, however, the third party's
12
call must first be routed through the CO
13
, via communication link
14
. Next, the CO
13
sends two signals
15
(a subscriber alerting signal (SAS) and a CPE alerting signal (CAS)) to the subscriber
10
, alerting the subscriber of the incoming telephone call from the third party
12
. The subscriber's
10
telephone unit then sends an acknowledgement signal
16
back to the CO
13
, alerting the CO that it is ready to accept the Type II CID data
17
. The CO then sends the data
17
to the subscriber
10
, where it is displayed and whereby the subscriber may make an informed decision as to whether the call between him or herself
10
and the second party
11
should be interrupted in favor of the call from third party
12
.
Turning now to
FIG. 2
, a flowchart depicts, in more detail, the above described handshaking between the CO
13
and the subscriber's
10
telephone unit. Similar to
FIG. 1
, the process begins with a telephone call being placed from a third party
12
to the subscriber's telephone at step S
1
; the subscriber's telephone unit being well known in the art as customer premise equipment (CPE). Next, the CO
13
directly receives the call from the third party at step S
2
. Next, the CO
13
determines whether the called CPE
10
is currently in use at step S
3
. If the CO
13
determines that the CPE
10
is not in use, the call is forwarded directly to the CPE
10
at step S
4
. However, if the CO
13
determines that the called CPE
10
is currently in use, a subscriber alerting signal (SAS), and a CPE alerting signal (CAS) are sent to the CPE
10
at step S
5
. The SAS is a low frequency tone (e.g., 440 Hz), audible to the subscriber only. The SAS lasts for approximately 300 ms and serves to alert the subscriber of the incoming telephone call. The CAS is a dual-tone signal combination, both being of fairly high frequency (e.g., 2130 Hz and 2750 Hz, respectively) and lasting for approximately 80 ms, or long enough to alert the CPE of the incoming telephone call. Additionally, the CO
13
temporarily removes the second party
11
from the current call during the transmission of the SAS and CAS. Next, the CPE
10
actually receives the signal pair (i.e., the SAS and CAS)
15
at step S
6
.
The CPE
10
must now decide whether it is prepared to receive the CID data. In so deciding, the CPE
10
determines whether any additional extensions on the same telephone line are currently in use (i.e., in addition to the CPE) at step S
7
. Most CPE manufacturers detect whether other extension(s) are off-hook by monitoring the line voltage. If the line voltage drops below a certain value, the CPE assumes there is another extension off-hook. If there is another device (or devices) in use, they all receive the SAS/CAS signal pair
15
concurrently with the CPE. The CPE
10
, however, cannot at that time accept the CID data because all off-hook units, including all extensions, must be muted in order to receive the CID data and as the state of the art currently exists, the CPE
10
is incapable of muting other off-hook units. Therefore, the CPE
10
will continuously check to see if the other extensions have been deactivated (i.e., placed back on-hook), so as to enable the receipt of CID data by all CID-capable telephones coupled to a common telephone line.
If the CPE
10
is the only telephone currently off-hook, the CPE
10
will then mute the CPE handset at step S
8
in preparation for sending acknowledgment signals back to the CO
13
, thereby alerting the CO
13
that it is prepared to receive the CID data
17
. The acknowledgement signals are s
Ali Syed S.
Berthoud Charles William
Agere Systems Guardian Corp.
Bost Dwayne
Dickstein , Shapiro, Morin & Oshinsky, LLP
Gelin Jean A
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