Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CALL MANAGEMENT SERVICES TO TELEPHONE DEVICES
WHICH ARE CONNECTED TO A FIXED WIRELESS ACCESS
SUBSCRIBER UNIT
Field of the Invention
This invention relates to the communication systems which
provide analog telephony services via a two-wire analog subscriber
line (hereafter referred to as telephone subscriber line) wherein said
telephone subscriber line is not connected to a central office switch
10 using the conventional two-wire analog telephone subscriber line
interface. In particular, the invention is particularly suited for fixed
wireless access (FWA) applications which provide telephony
services to conventional telephone devices via a wireless
communications link.
This application is related to Pepper, Simulating Changes in
Telephone Subscriber Line, filed concurrently herewith, the
specification which is hereby incorporated by reference.
Background of the Invention
The use of wireless communication systems to provide
telephony service has been seen to provide several advantages over
conventional wireline networks. These advantages include speed of
deployment, lower cost of installation, and reduced maintenance of
outside plant.
Conventional cellular-like terminals can be used for
providing fixed wireless access (FWA) as well as conventional
mobile cellular telephony. However, in order to reduce costs it is
advantageous to use terminals designed for fixed wireless access
only. Cost savings can be achieved as such terminals do not require
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mobility (in the conventional cellular sense) and also can be larger as
a result.
To reduce costs further, a fixed wireless access terminal can
use existing cellular networks for providing telephony service and
hence there is no need to deploy a separate FWA cellular system.
Additionally, a FWA terminal can reuse the technology and
components originally designed for conventional cellular service.
Systems have been described for interfacing a standard
conventional wireline telephone to a radio transceiver to enable
10 such a standard telephone (or other device) to use the cellular
network for providing telephony service. Such an interface device
for connecting a cellular radio transceiver to a conventional
telephony device is not new. For example, U.S. Patent No. 4,658,096,
naming West et al as inventors, describes an interface arrangement
for connecting a conventional telephone set to a cellular transceiver
such that the cellular network can provide telephony service to such
a telephone set. This patent describes an interface which includes
means for automatically determining when the user of such a
telephone set has finished dialling, as the concept for connecting a
20 telephone to cellular transceiver was known in the "radio-patch" art.
The above cited West patent is known in the art, and has been cited
many times in subsequent patents dealing with further aspects of
connecting a cellular transceiver to a telephony device. Such
systems, which may be adequate for providing POTS (plain ordinary
telephone service) service, do not adequately support more
advanced features.
For example, conventional land line networks can provide
call management services (hereafter CMS), for example, Calling
Number Delivery (CND), Message Waiting Indicator, Time of day
3 0 delivery, Calling Line Identification (CLID), Dialable Directory
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Number (DN), Reason for Absence of DN, Reason for Redirection,
Call Qualifier, Name of Calling Party and Calling Identity on Call
Waiting (CIDCW) by means of messages sent to a telephone unit.
CLASSsM (Bellcore trademark) which is compliant with GR-30-CORE
(TR-NWT-000030), LSSGR: Voiceband Data Transmission Interface
(hereby incorporated by reference, along with cited documents) is a
known format for sending such messages. Using this method, the
central office switch, with the aid of an appropriately configured
subscriber line interface circuit, is able to send information to
10 subscribers using some form of data modulation scheme. Of course
other types of protocols can be used, and in this specification we will
generally refer to these services as call management services.
Furthermore, advanced cellular systems, for example, IS54B,
April 1992, EIA/TIA Cellular System Dual-Mode Mobile Station -
Base Station Compatibility Standard (hereby incorporated by
reference), also provide call management services/features. Thus,
suitably equipped cellular terminals compatible with IS54B can
receive and display, call management services information.
However, the wireless protocols are not compatible with the land
20 line call management services protocols. Thus, there exists a need
for providing call management services features to a standard
telephone which is coupled, via a suitable interface, to a wireless
network.
Summary of the Invention
One aspect of the invention provides for a method of
providing call management services to a conventional wireline
telephony device (or devices) which receive telephony services by
means of a fixed wireless access subscriber unit. Such a subscriber
30 unit (SU) includes a wireless transceiver for communicating with a
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wireless network and a telephone subscriber line interface which
connects to a telephone subscriber line to which the telephony
devices are connected. Such a subscriber unit is configured to carry
out the following steps. Upon receipt of an incoming message
(which typically occurs during call set up of an incoming call) the
subscriber unit evaluates whether call management services
information is present, and if so searches the message, according to
the wireless protocol for the CMS information and extracts the CMS
information. The SU then interprets the received information,
10 determines what information should be passed to the telephony
devices to the SU and produces a message containing the relevant
information which is then sent to the telephony devices via the
telephone subscriber line. According to a preferred embodiment, the
new message may contain information not present in the original
incoming message. This new information is retrieved from a user
selected directory stored within the SU. According to another
embodiment of the invention the SU may contain a plurality of
transceivers and a plurality of subscriber line interfaces wherein said
subscriber unit can effectively act as a wireless key system.
Brief Description of the Drawings
The present invention, together with further objects and
advantages thereof will be further understood from the following
description of example embodiments with reference to the drawings
in which:
Figure 1 is a schematic representation illustrating how a
wireless communication network can provide call management
services information to conventional telephone sets according to a
30 preferred embodiment of the present invention.
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Figure 2 is a block diagram showing the architecture of a
subscriber unit according to a preferred embodiment of the
nventlon.
Figure 3 is a schematic representation of the message flow
between components of the subscriber unit.
Figure 4 is a flow chart illustrating the steps carried out by the
10 baseband microcontroller according to a preferred embodiment of
the present invention.
Figure 5 is a flow chart representing the steps carried out by
the voice frequency microcontroller according to a preferred
embodiment of the present invention.
Detailed Description of the Preferred Embodiment
The present invention will be described with respect to a
preferred embodiment used in a fixed wireless access system. It
20 should be appreciated by a person skilled in the art that the
invention can also be utilized in other types of systems, for example,
fiberoptic, cable TV, etc. which provide telephony services by some
means other than a telephone subscriber line connected to a central
office switch using the conventional two-wire analog telephone
subscriber line interface.
By way of example, Figure 1 illustrates a communications
network 1000 which in this example includes a wireless base station
which communicates by a medium 1100, which in this example is a
suitable radio frequency interface (e.g., IS54B), with a subscriber unit
(SU) 1200. Subscriber unit 1200 includes a communication interface
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which communicates with the communication network 1000 via the
medium 1100. In this example, communication interface comprises
a radio transceiver and antenna 1215 for communicating using IS54B
protocols with base station 345. Subscriber unit 1200 also includes
terminal unit which includes a primary handset 1240 and a SLIC
1230 which connects to telephone subscriber line 1250 which
connects to telephone 380. Additional telephony devices (not
shown) can be connected to the line 1250. Telephone subscriber line
1250 can include wiring within a building, extension wires, or a
combination thereof.
Figure 1 also illustrates an example of the SU 1200 receiving a
call from a telephone connected to the PSTN. In this example a
telephone 310 connects with a PSTN Central Office 340 which in
turn is coupled to an MSC 342 which is coupled to a base transmitter
station BTS (in this example via a BSC 345) which transmits via
antenna 350. Subscriber unit 1200 is coupled to a conventional
telephone set 380 which supports call management services features.
In operation central office 340 sends call management services
information to the MSC 342 about telephone 310 when telephone
310 attempts to place a call to subscriber unit 1200. This information
320 is formatted according to the specific trunk protocol used to
connect the PSTN 340 to the MSC 342. This information is
translated from the trunk protocol to the IS54B protocol by the MSC
342. The information in IS54B form is then transmitted, as shown at
360 in the form of an "alert with info" message sent over the radio
link from the base station to the subscriber unit after completion of
the paging process. The SU 1200 receives the IS54B coded message
over the air interface and then decodes said message to extract the
desired call management services information (e.g. calling party
3 o number). This decoding process is performed by the baseband
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microcontroller 90 and sent to the VF microcontroller 180 in an
intermediate format (as described below). The VF microcontroller
then carries out several central office functions as will be described
below in order to send a CLASS message 375 during the silent
interval between the first ringing period and the second ringing
period to the telephone 380. The conventional (but CLASS enabled)
telephone 380 then receives and displays the Call management
services information in the same manner as if the telephone 380 was
attached to a central office via a conventional two-wire analog
10 telephone subscriber line interface.
Thus, the terminal has in effect recoded the call management
services information contained in the IS54B messaging protocol into
an actual CLASS message (e.g., a Bellcore GR-30-CORE compliant
format) and then sent that CLASS message to the extension
telephone via the RJ-11 jack 230.
A subscriber unit 1200 according to a preferred embodiment of
the invention is shown in Figure 2 wherein the communications
interface comprises a radio block 10 and a baseband block 60, and the
subscriber unit also comprises a voice frequency block 110. There are
2 o two interfaces between the baseband block 60 and the voice frequency
block 110. The first interface, called the PCM interface 175 comprises
the digitized voice frequency pulse code modulation (PCM) transmit
and receive signals, while the second interface is a bi-directional
serial communications interface 178. The radio block 10 and the
baseband block 60 provide the conversion between the radio
frequency and digitized voice frequency signals. The baseband block
60 is also responsible for handling the protocols associated with the
RF link (e.g. IS54B) under the control of the voice frequency block
110.
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The voice frequency block 110 includes a primary user
interface which includes a display 120 for displaying, for example
calling line ID, a keypad 130, an alerter 150 which produces an audio
alert (e.g., ringing), an indicator which provides visual alerts (e.g., a
light indicator indicating, for example, that an extension is off hook
or that an incoming call has been received), and a primary handset
140. The voice frequency block 110 also includes a secondary user
interface including RJ-11 jack 230 which acts as an extension jack for
standard analog telephony devices. Note that an additional data jack
for a peripheral device, for example, a facsimile or modem device
can be supported.
Not shown is a suitable DC power source. This can comprise a
battery, or a suitable AC power adapter, or preferably a combination
of the two where ordinarily power is provided from an AC main
with battery power as a backup.
The voice frequency (VF) microcontroller 180 controls call
processing via input from the baseband block 60, the primary hook
switch 190, the keypad 130, the VF DSP 170, and the subscriber line
interface circuit (SLIC) 210. The VF microcontroller controls call
2 0 processing via control of the baseband block 60, the display 120, the
alerter 150, the VF DSP 170, and the SLIC 210. The VF
microcontroller includes a microprocessor and associated memory.
The Mitsubishi M37510 is a suitable VF microcontroller. The VF
microcontroller 180 communicates with the VF DSP 170 using a bi-
directional serial communications interface. The VF DSP 170
primarily provides the interface of the digitized voice frequency
transmit and receive signals between two pulse code modulation
(PCM) coder/decoders (CODEC) 160 and 200 and the baseband PCM
interface. The Analog Devices ADSP-2163 is a suitable DSP. PCM
3 0 CODEC 160 provides suitable analog to digital and digital to analog
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conversion between the primary handset 140 and the VF DSP 170.
Likewise, the PCM CODEC 200 provides suitable analog to digital and
digital to analog conversion between the extension devices via the
SLIC 210 and the VF DSP 170.
The SLIC 210, which for example can include an Advanced
Micro Devices AM79R79 SLIC chip, provides central office subscriber
line interface features to extension devices connected to the RJ-11
jack 230, via the tip and ring terminals. For example, the SLIC
provides over-voltage protection, DC power (battery feed), the hybrid
10 function (2 wire-4 wire interface), ringing voltage, supervision (off
hook detection), on-hook transmission etc.
In operation, a communication signal is received at both the
main antenna 20 and the diversity antenna 25, where the signal is
suitably filtered either by the RF duplexer 30 or the band pass filter 27
respectively. The RF switch 35 determines which of the signals are
downconverted by the receiver block 50 based on suitable diversity
selection process.
The selected signal is downconverted to a suitable IF signal by
the receiver block 50. The receiver block 50 also measures the
20 received signal strength and sends a message to the RF demodulator
and baseband interface block 70 as to the received signal strength
indication (RSSI) as is known in the art. The RSSI is then sent to the
baseband microcontroller 90. The baseband DSP 80 also determines
the bit error rate (BER) which is also forwarded to the baseband
microcontroller.
The baseband microcontroller 90 is used to process layers 1 to 3
of the communication protocol stack (e.g. IS54B), to manage the
control of the RF radio block 10 and the baseband block 60, to process
OA&M requirements and also carries out some user interface
30 functions via commands received from the VF microcontroller 180.
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These user interface functions, for example, include received signal
strength indication (RSSI) measurements and DTMF/call progress
tone generation.
Additionally, during reception of an incoming call, baseband
microcontroller 90 decodes the IS54B "Alert With Info" message,
pulls out the relevant class management services information
bundles (e.g., calling party number) and forwards this to the VF
microcontroller 180 in a suitable intermediate messaging format
which the VF microcontroller 180 uses to generate the CLASS
10 calling line identification information packet. The baseband
microcontroller 90 decodes other IS54B messages in a similar way to
provide information for other CLASS features such as message
waiting notification.
Upon receipt of an incoming call notification message from
the baseband microcontroller 90 the voice frequency microcontroller
180 sends an alert signal to the alerter 150, activating the alerter for
producing ringing at the primary handset. The VF microcontroller
180 also passes control information to the VF DSP 170 which in turn
is connected to the SLIC chip 210 which generates ringing voltage the
2 0 telephone subscriber line via extension voice jack 230. The VF
microcontroller 180 controls the user interface (e.g. ring cadence),
while the VF DSP 170 performs simple tasks based on commands
from the VF microcontroller 180.
As will be discussed in more detail, when the VF
microcontroller 180 receives the decoded call management services
information bundles from the baseband microcontroller 90, the VF
microcontroller 180 converts this information into the format used
by the extension telephone 380, for example, a CLASS formatted
message which in this example is then frequency shift keying (FSK)
30 modulated by the VF DSP 170 for providing CLASS information to
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the extension device. This CLASS calling line identification
information is sent to the extension devices, preferably during the
silent interval between the first and second ring signals in
accordance with GR-30-CORE.
We will now look at a more detailed example of how SU 1200
applies the above described method, with reference to Figures 3, 4a,
4b, 4c, 5a and 5b. Figures 4a, 4b and 4c show the processing steps
applied by the baseband microcontroller 90, while Figures 5a and 5b
show the processing steps applied by the VF microcontroller. It
10 should be appreciated by a person skilled in the art that these figures
are for illustrative purposes only and that they do not attempt to
cover all of the state transitions or actions performed while
receiving an incoming call in an IS54B environment. As well, this
example only covers the situation where the incoming call is
assigned to a digital traffic channel. A similar method is also
employed when the incoming call is assigned to an analog voice
channel.
Referring to Figures 4a, 4b and 4c, the baseband
microcontroller 90 will start in the "Idle" state 5100. Once a
20 successful page is received from the network 5110, the baseband
microcontroller 90 acknowledges the page 5120 and enters the
"Await Message" state 5200. Once in the "Await Message" state 5200,
the system will assign a traffic channel 5210 to the SU 1200, to which
the baseband microcontroller 90 will tune 5220 and then move to the
"Waiting for Order" state 5300 mode. While in the "Waiting for
Order" state 5300 the SU waits for the network to send a forward
digital traffic channel message, e.g., "Alert with Info" message 5310
(also shown as 360 in Figure 3). When the SU 1200 receives this
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"alert with info" message, the baseband microcontroller 90 sends an
"Alert On" message 5320 to the VF microcontroller 180. The
baseband microcontroller 90 then checks to see if the "Alert with
Info" message contains the "Calling Party Number" optional
information element 5330 about terminal 310. The optional
information element is optional as it is typically only sent in the
"alert with info" message if the user of SU 1200 subscribes to the
appropriate network services. For the purposes of this example, it is
assumed that the optional information element is sent in the "alert
10 with info" message. If no "Calling Party Number" is available, the
baseband microcontroller 90 is finished with the processing of the
"alert with info" message and it advances to the "Wait for Answer"
state 5350. If "Calling Party Number" is available, the baseband
microcontroller 90 decodes and forwards this information in an
intermediate format to the VF microcontroller 180 in a "Calling Line
ID" message 5340. In this embodiment, the baseband
microcontroller 90 performs no special mapping functions in
translating the "Calling Party Number" information into the
intermediate format for the VF microcontroller 180. Rather, the
20 baseband microcontroller looks at incoming bit stream containing
the calling party number, extracts the appropriate bits and then
reformats the bits into a byte oriented message which is then
forwarded to the VF microcontroller. It is the responsibility of the
VF microcontroller 180 to provide the necessary translations to
convert the "Calling Party Number" information into a valid CLASS
message. The details of the intermediate message format and the
rules applied to translate from "Calling Party Number" to CLASS
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(GR-30-CORE) will be described in detail below. The baseband
microcontroller 90 sends an "alert on" message whenever it receives
the "alert with info" message over the radio link. It will only send
the "calling line id" message if the optional information element
"Calling Party Number" is received.
Referring to Figures 5a and 5b, the VF microcontroller 180
starts in its initial "Idle" state 6100. The VF microcontroller 180,
upon receiving the "Alert On" message 6110, advances to the
"Alerting" state 6120. The VF microcontroller 180 enters the
10 "Alerting" state 6200 and starts the normal ring timing sequence
which alerts the user to an incoming call (typically 2 seconds on, 4
seconds off) and starts a "CLASS Delivery Timer" 6210 to determine
when to send the CLASS encoded information to the RJ-11 interface.
The "CLASS Delivery Timer" is set to timeout at the end of the first
ring signal plus 500 msecs. The intent is to send the CLASS message
burst to the extension set in the silent interval between the first and
second ring signal, at least 500 msecs after the end of the ring tone in
accordance with GR-30-CORE. While in the "Alerting" state, four
different events may occur. The VF microcontroller 180 may receive
20 a "Calling Line ID" message, the user may answer the call, the far
end calling party may release the call which would result in an
"Alert Off" message or the "CLASS Delivery Timer" may expire.
The following describes how each event is handled.
In this embodiment, the VF microcontroller 180, upon
receiving the "calling line id" message 6220, decodes the information
(e.g., calling number and/or calling name or private number etc.)
and displays this information on the primary display 120 as shown at
6230. It also saves this data for subsequent translation into a CLASS
encoded message and transmission to the extension sets should the
3 o CLASS Delivery Timer expire. If the user of the SU 1200 answers the
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14
call 6240, the VF microcontroller 180 stops the CLASS Delivery
Timer and goes to the "Conversation" state 6250. If the CLASS
Delivery Timer expires 6260, the VF microcontroller 180 verifies that
it has valid "Calling Line ID" data available 6270. If no data is
available, no actions are performed. If data is available, the VF
microcontroller 180 performs the CLASS message coding and
assembly as discussed in more detail below and sends a multiple data
message format message on to the VF DSP 170 which FSK modulates
the microcontroller data, establishes the correct signal amplitude, all
according to Bellcore GR-30-CORE, and then sends the FSK
modulated message to the SLIC for transmission to the extension
6280. In this embodiment, the VF microcontroller 180 controls all
aspects of the transmission except for the actual data modulation.
That is, the VF microcontroller 180 specifies the amplitude of the
modulated signal to use for transmission, what timing parameters to
use, when to generate the signal as well as the proper coding of the
information including checksums. Finally, if the VF
microcontroller 180 receives an "Alert Off" message 6290, this is an
indication that the call has been released. The VF microcontroller
2 0 180 then stops alerting the user and goes back to the Idle state 6300.
It should be noted that if the SU 1200 is in the "Conversation"
task, a "Flash with Info" message can be received if the SU 1200 user
is a call waiting subscriber.
As stated, the baseband microcontroller 90 is responsible for
processing layers 1 to 3 of IS54B. The messages of IS54B, for example
"alert with info", are sent in a bit packed format. When translating
the "alert with info" message from IS54B to the intermediate format,
the baseband microcontroller 90 extracts the relevant bits from the
"calling party number" information bitstream and rebundles them
into a byte oriented protocol suitable for the VF microcontroller 180
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to process. The baseband microcontroller 90 forwards the following
pieces of information (sent in the "calling party number" field of the
"alert with info" message as described in the IS54B specification):
~ Screening Indicator bits
~ Presentation Indicator bits
~ Type of Number
~ Numbering Plan Identification
~ Character(s)
Note that there may be two instances of "calling party
10 number" in the "alert with info" message in which case the
baseband microcontroller 90 would send two bundles of information
as specified above. Also, it should be appreciated by a person skilled
in the art that a similar message could be received when the SU 1200
is sent a "flash with info" message for implementing such features
as CIDCW for example. The above parameters are coded as follows
(as described in the IS54B specification).
The Screening Indicator bits (SI bits) are defined as:
Code Description
00 User-provide d, not screened.
01 User-provided, verified and passed.
User-provided, verified and failed.
11 Network-provided.
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16
The Presentation Indicator bits (PI bits) are defined as:
Code Description
00 Presentation allowed.
01 Presentation restricted.
10 Number not available.
11 Reserved.
The Type of Number bits are defined as:
Code Description
000 Unknown.
001 International number.
010 National number.
011 Network-specific number.
100 Subscriber number.
101 Reserved.
110 Abbreviated number.
111 Reserved for extension.
The Numbering Plan Identification bits are defined as:
Code Description
0000 Unknown.
0001 ISDN/Telephony numbering plan (CCITT E.164 and E.163).
0011 Data numbering plan (CCITT X.121).
0100 Telex numbering plan (CCITT F.69).
1001 Private numbering plan.
1111 Reserved for extension.
All other values reserved.
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When the VF microcontroller 180 receives the "Calling Line
ID" message from the baseband microcontroller 90, it decodes and
maps the IS54B suppIied information into appropriate CLASS
information. This CLASS message includes a time parameter
(which the SU 1200 obtains from its internal clock (not shown)),
either the dialable DN (DDN) of the calling line or the Reason for
Absence of DN (e.g. "Private Number" or "Out of Area"), and the
name parameter if either the name information is sent over the
cellular infrastructure or an incoming preferred name match
occurred (explained below). The VF microcontroller 180 encodes the
CLASS message using the "multiple data" messaging format,
specifically the "call set up" message, and includes the appropriate
fields as stated above (e.g. Time, DDN, Name, Reason for Absence of
DN). These parameters are defined in GR-30-CORE or documents
cited therein. In the preferred embodiment, the following rules are
applied by the VF microcontroller to determine what information to
send in the CLASS encoded (GR-30-CORE) message. Note that in the
preferred embodiment, the VF microcontroller does not process the
SI bits, the Type of Number bits or the Numbering Plan
2 o Identification bits.
The VF microcontroller 180 interprets the PI bits as follows:
~ If "presentation is allowed", interpret the rest of the data (e.g. the
characters) as specified below.
~ If "presentation is restricted", send a CLASS call set up message to
the extensions encoded as Reason for Absence = Private Number,
Time = Current local Set Time/Date (no DDN, no Name etc.).
~ If "number is not available", send a CLASS call set up message to
the extensions encoded as Reason for Absence = Out of Area,
Time = Current local Set Time/Date (no DDN, no Name etc.).
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18
~ If "presentation is reserved" ignore any additional information
in the remaining fields. Don't send any CLASS information to
the extensions.
The CLASS messaging protocol provides well defined fields
for calling line identification such as Calling Number Delivery
(CND), Time of day, Calling Line Identification (CLID), Dialable
Directory Number (DN), Reason for Absence of DN, Reason for
Redirection, Call Qualifier and Name of Calling Party. IS54B,
10 however, does not provide such unique qualifiers. Instead IS54B
provides the SI, PI, Type of Number and Number Plan Identification
bits and "characters". The characters can be digits, for example the
directory number (DN) of the calling party or possibly an ASCII
encoded name for example. The VF microcontroller 180 must
therefore apply several rules to the "character" information to
determine what to send to the extension sets. There are essentially
three cases to consider: 0,1 and 2 instances of "calling party number".
Case 1: Zero instances of "calling party number" information
2 0 is received.
~ Discard all information and do not send CLASS information to
extension sets.
Case 2: One instance of "calling party number" information is
received.
~ Examine the PI bits and handle as specified above.
~ If PI bits are "presentation allowed" continue.
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19
~ If all characters are "digits" (0,1,...,9), treat the information as
DDN and perform preferred name matching (described below). If
preferred name matching passes, send a CLASS call set up
message with DDN = characters (digits) received, Name = output
of preferred name match and Time = Current local Set
Time/Date.
~ If the above test fails, treat the information as "Name", send a
CLASS message with Name = characters received and Time =
Current local Set Time/Date (no DDN or Reason for Absence).
Case 3: Two instances of "calling party number" information
is received.
~ Examine the PI bits and handle as specified above.
~ If PI bits are "presentation allowed" continue.
~ If all characters of first instance are "digits" (0,1,...,9), treat the
information as DDN, second instance shall automatically be
treated as "Name". Perform an incoming preferred name match
and if the name match passes, replace instance 2 with the
preferred name. Send a CLASS message with DDN = characters
(digits) received from instance 1, Name = instance 2 (or output of
preferred name match) and Time = Current local Set Time/Date.
~ If the above test fails, i.e. the first instance is not "digits" only, log
first instance as Name then check second instance. If all
characters of second instance are "digits" (0,1,...,9), treat the second
instance as DDN. Perform an incoming preferred name match
on the second instance and if the name match passes, replace
instance 1 with the preferred name. Send a CLASS message with
DDN = characters (digits) received from instance 2, Name =
instance 1 (or output of preferred name match) and Time =
Current local Set Time/Date.
- CA 0221943~ 1997-10-24
~ If the above test fails, i.e. the second instance is not "digits" only,
discard second instance. Send a CLASS message with Name =
instance 1 and Time = Current local Set Time/Date (no DDN or
Reason for Absence).
In order to send this CLASS message to the extension sets, the
VF microcontroller 180 encodes each parameter (DDN, Time, Name,
Reason for Absence) including lengths and checksums. Additionally
the VF microcontroller formats the message to provide proper
10 conditioning as specified in GR-30-CORE, for example channel
seizure and mark signal. The resultant output of the modulator is
presented in Figure 3. The resultant data is then sent to the VF DSP
170 where the FSK message stream is transmitted in the silent
interval between the first and second ringing sequence which the
SLIC applies to the telephone subscriber line.
In this context the Fixed Wireless Telephone can be viewed as
the Stored Program Controlled Switching System (SCPS) and the
extension telephone as the Customer Premises Equipment (CPE)
since the central office CLASS messaging delivery function has been
effectively moved over to the subscriber unit.
Preferably the subscriber unit 1200 has local features for
customizing the terminal for the user. For example, the SU 1200
primary interface includes several personalized memory dialer keys
and provides the user with the ability to program a personalized
directory of directory numbers (DN) and Names associated with each
DN. The name is programmed by the user of the SU 1200 and can be
any name chosen by the user, i.e. it is the preferred name for the
called party of the associated DN. This name is presented to the user
(via the display 120) when the user of the SU 1200 sets up a call from
3 0 the directory or memory dialer. Many wireless networks, which
CA 0221943~ 1997-10-24
deliver the DN of the calling party, do not deliver the Name of the
calling party. To enhance the usefulness of this unit, the VF
microcontroller 180 preferably performs an incoming name match of
the delivered DN (if available). The VF microcontroller does this by
comparing the incoming DN (sent in the IS54B "alert with info"
message) with each DN in the directory and the memory keys until
either an identical match is found or all entries have been compared
and failed. If a match between the incoming calling party number
and a directory entry number or memory dialer number is made, the
10 VF microcontroller 180, uses the associated name of the matching
entry as the "preferred" name to display locally (on display 120) and
to send as a "Name" parameter in the CLASS message directed to the
extension. This preferred name will either replace any name that
was sent in the "alert with info" message, or it will add a name
when none was sent.
It should be noted that other components and features of the
SU may be included but have not been described. For example, the
hardware of the SU according to a preferred embodiment also
includes the capability for tip and ring reversal control, tip and ring
20 open circuit control, on-hook and off-hook transmission capability,
dual tone multi-frequency (DTMF) generation and detection
capability as well as some form of data modulation/demodulation.
It should be appreciated by a person skilled in the art that
several modifications could be made to the above embodiment. The
preferred embodiment uses two microcontrollers, one for processing
layers 1 to 3 of IS54B and one for controlling the VF section. It is
possible to combine both processors and perform all tasks in the one
controller. Also, there is no need for the SU 1200 to be a combined
handset and SLIC. The invention could also be implemented in a
30 system which provides no primary user interface (e.g. no local
CA 0221943~ 1997-10-24
handset), i.e. a box that provides wireless to SLIC access only. In such
a system the user must attach an external telephone device (to the
SLIC) to get telephony service.
The preferred embodiment describes the method of
converting IS54B to CLASS (GR-30-CORE). In general, similar
methods could be employed to convert other radio technologies (e.g.
IS95,...) or other access technologies (e.g. cable connection to PSTN
instead of wireless). Similarly, the CLASS messaging could be
replaced with other forms of CMS delivery to two-wire analog
10 subscriber lines which utilize such things as tone signalling,
modulation techniques and tip/ring reversal or open switch interval
(OSI) signalling. For such systems the following, e.g., tip and ring
open circuit control, on-hook and off-hook transmission capability,
dual tone multi-frequency (DTMF) generation and detection
capability as well as some form of data modulation/demodulation
may be required. Additionally, although CLASS calling line
identification has been described above, other CLASS features can be
implemented for example using the IS54B message waiting
signalling (contained in "mobile station control" and "flash with
20 info" messages) to deliver CLASS message waiting to the extension
sets.
Furthermore, the preferred embodiment uses the multiple
data message format for delivering Call Setup information. This
could be implemented using, for example, single data message
format with Calling Number Delivery or Message Waiting Indicator.
Also, although the SU 1200 has an RJ-11 jack, other coupling jack
arrangements can be used.
Numerous modifications, variations and adaptations may be
made to the particular embodiments of the invention described
CA 02219435 1997-10-24
above without departing from the scope of the invention, which is
defined in the claims.
