Simultaneous voice and data communications system

A communications system for simultaneously conveying voice and data messages is provided in accordance with the teachings of the present invention. In the communications system disclosed a ring transmission medium for the serial transmission of message information is provided. A plurality of taps are disposed along the ring transmission medium and each of the plurality of taps acts to receive connections from a communications module having at least an input and an output and acts to connect the communications module to the ring. Each of the plurality of taps is configured to have its inputs and outputs connected to the ring and act when no communication module is connected thereto to convey message information on the ring directly between the input and outputs of the tap. When a communications module is connected to that tap, message information is applied from the ring to the input of the communications module and from the output of the communications module to the ring transmission medium. A plurality of individual telephone stations for communicating voice messages are connected to the ring through individual ones of the taps wherein each of the telephone stations takes the form of a communications module having a basic component nucleus for interfacing with the ring and at least one additional component for performing telephone station functions. A data access unit for connection to one of the plurality of taps acts to couple data messages to the ring. The data access unit also includes the basic component nucleus for interfacing with the ring and at least a further component for coding digital data applied thereto. The data access unit may be connected to terminal devices or the like.

BACKGROUND OF THE INVENTION 
The present invention relates to a simultaneous voice and data 
communications system using telephone stations and data terminal 
equipments, with possibility of connection to public or private networks. 
Business communication systems have undergone an evolution which, starting 
from electromechanical systems with voice communication services, have 
developed to advanced systems, providing an integral solution to the 
communications requirements in office automation. 
The first systems to be considered when analyzing the generic problem of 
communication in offices, are those fundamentally concerning voice 
switching. These systems in almost all cases have adopted one of the 
following configurations: 
(1) PABX 
This solution copies the architecture, and in many cases the equipment of 
public telephone exchanges and makes use of them to comply with the 
requirements of private organizations. 
The PABX's have the following characteristics: 
The centralized configuration which they use is a cause of high fixed 
costs, which can only be compensated by the installation of a high number 
of subscribers. However they are optimum when the number of subscribers is 
very large. 
The installation is quite rigid as it is made by means of line pairs 
asigned to each subscriber. Modifications of the configuration require 
changes implying service interruptions, and also specialized personnel. 
They are intended for voice services. Data services are included at high 
cost, and with bandwidth limitations in analogic exchanges. Digital PABX's 
pretend to offer access to data services in a more easy way. 
Normally they offer a wide range of net facilities (abbreviated selection, 
access to closed groups, etc.) They seldom offer the possibility of 
connection of multifeature telephones. 
The PABX's fundamentally are connected to the switched public telephone 
network. Normally they do not provide access to public or private data 
networks. 
(2) Key Systems 
In those cases in which the number of telephone sets does not justify the 
cost of a PABX, where the functions of a telephone operator must be shared 
by several subscriber's positions, or when it is desired to simplify 
access, both internal and external, and provide more complete signaling 
the normally offered solutions are within the key system category. Key 
systems have the following characteristics. 
Most of them are electromechanical and their normal structure is as a 
multiwire bus from which the individual terminals are connected. They are, 
in general, of small capacity, and whithin this range, they become more 
economical than a PABX. 
Normally they are systems provided with blocking as the bus usually 
provides fewer circuits than connected terminals. 
The installation is rigid, in as much as the location of the terminals on 
the bus is not easily modificable. Thus normally a physical modification 
of the equipment is required, and consequently, the system must be taken 
out of service placement to achieve the modification. 
They do not include data services. 
Normally they only provide the facilities peculiar to these type of 
systems, such as: complete signaling of all positions, transfer 
facilities, multi-operator, etc., but do not include extra facilities, 
(directory, agenda, etc.) 
Normally they are connected to the public switched telephone network or to 
a PABX. 
These systems are fundamentally intended for voice switching and have a 
long record in the office communication systems market. 
Recently, local area networks have been developed. The notion of a local 
area network (LAN) has become popular for several reasons. The most 
evident reason being the suitability of providing a mechanism to allow 
equipment from different manufacturers, to be inter-connected through a 
common communication media. In this way, mini-processors, terminals, 
personal computers, text processors, mass memory devices, printers, etc, 
can be linked. 
At the present moment, basically, there are two protocols for local area 
networks defined by the 802 Commision of the IEEE. The first of them is 
the CSMA/CD (Carrier Sense Multiple Access/Collision Detection). The first 
is a packet broadcast system based on Ethernet (industry standard proposed 
by Digital Equipment, Intel, and Zerox). The second is the "Token Passing" 
system supported by IBM. However, none of these protocols have been 
designed for an efficient and economic handling of voice signals. Local 
area networks have the following general characteristics: 
Very wide connectability range, from very few, to hundreds or thousands of 
terminals. There are diverse architectures, topologies (ring, bus, star) 
and mechanisms of access (protocols). In general, they often are more 
costly than the equivalent voice systems. 
Usually they are systems employing blocking with a statistical use of the 
available bandwidth, even during connection. 
They usually are very flexible systems, in their installation, and 
reconfiguration, particularly as compared with conventional data systems. 
They are not intended for voice handling, due to the statistical nature of 
information transfers. 
They provide a wide range of data services and facilities including added 
value functions, that increase the capabilities of the basic service. 
The range of terminal devices connected, depends on the manufacturer, but 
in general, it is very wide. 
They are normally connected to public data networks, or otherwise to other 
terminal devices associated wtih public switched telephone networks by 
means of vocal band modems. 
SUMMARY OF THE INVENTION 
The new simultaneous voice and data communications system, with possibility 
of connection to public or private networks, which is the object of the 
present invention, is intended to provide an integrated communications 
system to be utilized in offices or the like, having the advantages of 
each of the above described systems, but not incurring in their 
disadvantages. 
The characteristics and/or advantages of the new system are: 
It is a simultaneous voice and data communications system, with possibility 
of connection to public or private networks. The system is completely 
modular, and the cost depends exclusively on the number of equipped 
stations. It may be applied to large offices, by adding interconnected 
systems. 
The system provides a flexible installation which is easy to connect, and 
reconfigure. 
The system provides simultaneous voice and data services. The interfacing 
and protocols required for data service do not penalize the telephone 
service. 
The system provides a wide range of voice facilities. In addition to having 
all of the characteristics of a key system, it offers a user "friendly" 
mode of operation that guides a user through a host of system features 
such as abbreviated dialing, agenda, directory, clock, etc. 
The connection of a data terminal is simple and flexible. The protocols and 
formats satisfy the requirements of the present market (RS 232-C, BSC, 
SDLC, etc.). If the user so requires, additional feature modules may be 
added. 
The hardware is universal, and its adaptation depends on the software. 
The system may be connected to the following networks: 
Public switched telephone networks both for voice and data services. In the 
second case, voice band modems are used. 
Private telephone networks 
Public data networks, both circuit switched and packet switched. 
Local area networks. 
Integrated services digital networks (ISDN)

DETAILED DESCRIPTION 
In the different figures, use has been made of corresponding reference 
numerals symbols for designating structural elements as follows: 
11--Ring 
12--Tap point to the ring for the different units of the system 
13--Line unit (one of the units of the system) 
14--Telephone station (another of the units of the system) 
15--Data access unit (another of the system's units) 
16--Any other future interface (future units of the system) 
17--Power supply for the system 
18--Power connection to the electrical mains 
19--External link, subscriber's loop or PBX extension line. 
20--Connection to a data terminal interface 
21--Connection to the data terminal interface. 
22--Connection to a voice interface in a telephone station 
23--Connection to a multiplexing interface in a lines unit. 
24--Connection to a parallel control interface. 
25--Connection to a series control interface 
41--Data input by the user, by means of push button unit 
42--Video signal connection 
43--Acoustic signal connection 
44--User interface 
45--Connection to data interface 
51--Connection to data terminal interface 
61--Modems with automatic call equipment 
62--Packet assembly/disassembly equipment 
63--Packet switched data network (PSON) 
64--Public switched telephone network (PSTN) 
65--Analog PABX 
66--Simultaneous voice and data communications system according to the 
present invention. 
CC/CC--DC/DC converter 
INC--Closed numbering interface 
I RDSI--ISON interface 
I X-25--X-25 interface 
##EQU1## 
MCC--Central control module MCD--Data coding module 
MCS--Synchronization and switching module 
MDC--Voice coding/decoding module 
MIC--Ring interface module 
MID--Data interface mocule 
MIL--Line interface module 
MIU--User interface module 
MLT.sub.1,n --1, n telephone line module 
MUX--Multiplexing module 
RDSI--Integrated services digital network 
Rs 232-C--RS 232-C interfac 
S(RDSI)--(ISON) S interface 
TD--Data terminal 
TD V-24--V-24 data terminal 
TD V-25--V-25 data terminal 
TD X-25--X-25 data terminal 
TN--Normal telephone set 
T DSI--ISON termination 
V-25--V-25 interface 
X-25--X-25 interface 
The new simultaneous voice and data communications system, with possibility 
of connection to public or private networks, is a PCM system with a ring 
topology, allowing connection to the ring of telephone terminals (Key 
systems, multifunction, etc.) and of data terminals (teleprinters, 
facsimile, etc.) with possibility of access to any type of external 
computer network. 
An important characteristic that must be emphasized, is that the new system 
according to this invention is the first commercial system providing 
simultaneous voice and data service, making use of techniques more related 
to digital telephony than to data systems to achieve this end. In addition 
it combines in a single product a digital telephone system and a local 
area network providing local area network services at low cost. 
The system is of modular design having distributed control, which makes the 
cost a linear function of the number of terminals. 
As shown in FIG. 1, the system consists of the following elements: the 
system ring (11), tap points (12) to the ring for the different units of 
the system, and the different units of the system line unit (13), the 
telephone station (14), the autonomous data interface (15), etc. FIG. 1 
additionally shows the general power supply for the system (17) which is 
connected to the electric main via plug and cord (18). The system output 
(19) for the external links, the subscriber loops, or the extension lines 
of a PBX are also illustrated. 
The ring consists of a physical support for the series transmission of the 
information (pair of wires, coaxial cable, optical fiber, ets.) which is 
achieved by means of pulse code modulation, and optionally by a pair of 
additional conductors intended for the supply of the different units of 
the system connected to the ring. As long as no use of tele-supply or 
local supply, of said units is made, the tap points (12) to the ring for 
the different units of the system, may be installed at any point along the 
ring and may be configured as a telephone type plug. 
When a tap point (12) has no unit connected, it allows propagation of the 
information from the input to the output, with no modification of the 
same. However, when a unit is connected to a tap point (12), the unit acts 
on the tap point (12) diverting the input information towards its own 
unit, and connecting the output of the same, to the physical support of 
the transmission (pair of wires, coaxial cable, optical fiber, etc.), in 
the out-going direction. The tap point (12), restores the ring continuity 
in case of disconnection of the unit, be it caused either by anomalous 
operation, failure or physical disconnection. 
The different units of the system, in accordance with the modular design of 
the same, are characterized in that all of them have a common portion, 
which will be referred as the "Basic Nucleus", and another portion which 
is specific for each type of unit. 
FIG. 2 shows a block diagram of the Basic Nucleus which is common to any 
unit to be connected to the ring. This Basic Nucleus consists of a DC/DC 
converter (CC/CC) and three functional modules: the ring interface module 
(MIC), the synchonization and switching module (MCS) and the central 
control module (MCC). 
The DC/DC converter (CC/CC) provides the modules of the units with the 
voltages and currents needed for their operation. Energizing potential for 
the DC/DC converter is obtained from input voltage from the external 
supply. 
The ring interface module (MIC) accomplishes the following functions: 
Insures correct bit transmission between active consecutive units of the 
ring, 
Decodes the information received from the input pair, and synchronizes the 
phase of its interior clock, with from clock information included in the 
input train bits, 
Delivers to the syncronization and switching module (MCS) the received 
clock and data, 
Codes the binary information from MCS module and sends it to the tap point 
to the ring. 
The syncronization and switching module (MCS) accomplishes the following 
functions: 
Alignment of frames received from the ring interface module (MIC) 
Multiplexing and demultiplexing of the informations included in the time 
slots of the frames. 
Storing of the contents of the frames in a buffer memory 
Switching to and from the outputs/inputs of voice and data of the 
corresponding bytes. 
Generates and sends to the ring interface module (MIC) the output frames 
with the new contents of the time slots. 
Supervises the quality of transmission of the received frames 
Provides, from the central control module (MCC), an orderly access to the 
information contained in the buffer memory. 
The central control module (MCC) accomplishes the following functions: 
Controls the operation of the unit 
Maintains an image of the state of the complete system as presently 
configured 
Maintains the internal signaling protocol 
Insures the dialog with the user in the telephone stations of the system. 
Controls the external lines in the lines units. 
FIG. 3 shows a block diagram of the line unit, which is one of the 
different units of the system, that may be connected to the ring. The 
lines units has for its function to connect the stations of the system to 
external telephone lines, either directly or through the extensions of a 
PBX, transforming the digital information of the stations into analog 
information. As may be seen from FIG. 3, the line unit consists of a Basic 
Nucleus, common to all the units of the system, and three additional 
modules: the line interface module (MIL), the telephone line modules (MLT) 
and the multiplexing module (MUX). 
The line interface module accomplishes the following functions: 
Interprets the in-coming call signaling from the different lines. 
Generates out-going call signaling towards the different lines 
Maintains proper timing 
The telephone line module (MLT), insures the adaptation of the digital 
signals generated by the system, to the signals accepted by the external 
telephone lines, or by the external links, and the converse thereof. 
The multiplexing module (MUX) combines, or separates, the informations 
from, or to, the different coders/decoders included in the different MLT 
modules. 
FIG. 4 shows a block diagram of a telephone station, which is another of 
the units of the system that may be connected to the ring. The telephone 
station provides for the design of a multifunction telephone station, with 
all the features of a telephone set, plus those provided by an 
alphanumeric display. Such features may include a general and private 
directory, personal agenda, calendar, clock, automatic dialing with 
repertoire, etc. Through the telephone station, data terminals may be 
connected. The telephone station consists of a Basic Nucleus as aforesaid, 
and three additional modules; the voice coding/decoding module (MDC), the 
user interface module (MIU), and the data interface module (MID). 
The voice coding/decoding module (MDC) accomplishes the following 
functions: 
Takes the digital samples received in the frames through the 
synchronization and switching module (MCS) of the Basic Nucleus, and 
converts them to an audible analog signal, delivered to the telephone 
receiver 
Takes the analogic signal generated by the microphone, codes it and 
transfers it to the synchronization and switching module (MCS) of the 
Basic Nucleus. 
The user interface module (MIU) accomplishes the following functions: 
Transfers the information inserted by the user by means of push buttons, to 
the central control module (MCC) of the Basic Nucleus. 
Provides the various acoustic signals 
Presents information to the user about the state of the system, and 
provides operating assistance by means of suitable video presentations. 
The data interface module (MID) transfers to and receives from data coding 
module (MCD), the information and control signals required for the correct 
operation of the latter. 
With the elements and units so far described, a basic telephone system 
would consist of the ring, a supply unit, a series of tap points, a line 
unit, and a series of telephone stations. 
However, the system also provides data services wholly equivalent to those 
provided by a local area network. In effect, by means of the corresponding 
interface, a great variety of terminals from different manufacturers may 
be connected to the ring in such a manner that the same may communicate 
with each other and have access to public or private external networks. 
FIG. 5 shows a block diagram of one of these interfaces, the data access 
unit. The data access unit consists of a Basic Nucleus (common to all 
units of the system) and a data coding module (MCD) that accomplishes the 
following functions: 
Procures the connection, use, and operation of channels for data use which 
are presented by the synchronisating module (MCS) of the Basic Nucleus, 
through the data interface module (MID) included in the MCD. 
Accomplishes data channel multiplexing/demultiplexing to or from the frame, 
and switching from or to the terminal elements. 
Transfers the data to or from the different remote terminal elements 
connected to the MCD module, directly or through external networks, either 
private or public, adapting itself in protocol, codes, and transmission 
characteristics to the requirements of the system, and of the terminal 
elements. 
Accomplishes when necessary, the control, and the procurement of any 
adapting element to external networks, either private or public. 
Controls the establishing and ending protocols of all the data 
communications. 
As a result of the modular structure of the system, the data coding module 
(MCD) may be directly connected to the data interface module (MID) of a 
telephone station. This provides a data interface at a much lower cost, as 
use is made of the Basic Nucleus for the telephone station. 
FIG. 6 shows a generic configuration of the simultaneous voice and data 
communication system according to the present invention which provides the 
possibility of connection to public or private networks. FIG. 6 readily 
indicates the enormous potential of the system. 
In FIG. 6 it may be seen that, connected to the ring are the voice 
telephone services (telephone stations, lines units, closed numbering 
interface) and data terminals. The data terminals are connected either 
through an autonomous data interface, or through a telephone station. 
In addition, as shown in FIG. 6, the data terminals may be connected to the 
ring of the system, with access to terminals or computers connected to the 
analog public switched telephone network provided, so long as they operate 
through appropriate modems. This is achieved through a data access unit, 
and with modems provided with automatic call equipment working in 
accordance with recommendation V-25 or the C.C.I.T.T. 
The figure shows also the connection to a packet switching data network, 
through an X-25 interface. 
Lastly, it is also posible, through corresponding interfaces, to connect to 
other digital systems, such as other ring systems as described in the 
present specification, as well as those associated with public exchanges 
or private branch exchanges, and to integrated services digital networks.