Mobile

A system is described for providing ISDN services on a PSTN to communication units from an ISDN interface within a resource controller. The communication unit is allowed access to a target such as a subscriber within the PSTN or a communication unit in another cell, in an ISDN environment through entry of a target access number. The ISDN environment may be changed by the communication unit before entry of a target ID number.

MICROFICHE APPENDIX 
This specification includes a microfiche appendix comprising 3 microfiche 
and 189 frames. 
COPYRIGHT INFORMATION 
A portion of the disclosure of this patent contains material that is 
subject to copyright protection. The copyright owner has no objection to 
the facsimile reproduction by anyone of the patent document of the patent 
disclosure as it appears in the Patent and Trademark Office patent files 
or records, but otherwise reserves all copyright rights whatsoever. 
FIELD OF THE INVENTION 
This invention relates to the field of communication systems and more 
specifically to trunked communication systems. 
BACKGROUND OF THE INVENTION 
Trunked radio communication systems are known. Such systems typically 
allocate communication resources to communication units upon a perception 
of a need for service by a resource controller. 
Transceivers are provided at communication system base sites to receive 
signals from communication units and to re-transmit the signals for the 
benefit of any target units present within the service coverage area of 
the base site. Some transceivers present at the base site are also capable 
of, upon occasion, providing an interconnect between the communication 
unit and a local public switched telephone network (PSTN). 
PSTNs are also known. PSTNs offer communication services primarily over 
wireline based communication facilities. Services offered include basic 
telephone service as well as a number of auxiliary services offered 
independently or through integrated services digital networks (ISDNs). 
ISDNs, as is known, offer a variety of voice and data services. 
Key to accessing ISDN services is the transmission of control characters 
into the PSTN system. Access to an ISDN system, and the type of service 
provided, is dependent upon providing the proper control words under 
protocols as follows: Q.931 for voice and data service, Q.932 for 
supplementary services, and X.25 for packet mode data servicing (for an 
detailed description of control of an ISDN system, refer to Bellcore--Bell 
Communication Research Pub. No. TR-TSY-000268 (Issue #3, May 1989)). 
In the past, creation of control characters and protocols for accessing 
ISDN services has been under the control of a computer (or data processing 
equipment with an AT&T SESS switch or Northern Telecom DMS switch) or 
other data processing equipment connected to the PSTN network and 
typically under the manual control of an operator. Because of the 
importance of ISDN services a need exists for access to ISDN on a PSTN 
from other communication systems. 
SUMMARY OF THE INVENTION 
Pursuant to one embodiment of the invention in a communication system 
having a resource controller with an ISDN interface and an interconnect to 
a PSTN offering ISDN services, and at least one communication unit 
requiring communication services involving ISDN services, a method of 
providing communication services to the requesting communication unit is 
offered. The method of providing the communication services to the 
communication unit involves transmitting an inbound communication to a 
resource controller at a base site from a requesting communication unit, 
receiving and decoding the inbound communication at the base site to 
produce an ID of a target. The ID of the target is communicated to the 
ISDN interface, which upon occasion, determines that an access code of the 
target is listed in a routing table within a memory operatively coupled to 
the ISDN interface. The ISDN interface recovers the access code from the 
routing table and a set of control words specifying an ISDN environment 
from a look-up table. The ISDN interface then transmits the access code 
and set of control words over the PSTN interconnect to an ISDN network 
within the PSTN system. 
In order for a requesting communication unit to access a target over an 
ISDN system the ISDN interface must first exchange information with the 
ISDN network relative to a communications environment. The communication 
environment may be created through the exchange of set-up commands with an 
ISDN network within the PSTN system. The set-up commands used by the ISDN 
interface are contained within a look-up table within the memory 
associated with the ISDN interface. Upon receipt of a request for access 
to a target over the ISDN network the ISDN interface first transmits a 
series of set-up commands into the ISDN network recovered from the ISDN 
environment look-up table. 
Changes may be made to the ISDN environment look-up table by activation of 
a change routine. In one embodiment, the change routine is activated by a 
communication unit by entry of a two digit code (token number) followed by 
activating a send button located on the communication unit. Activation of 
the change routine activates a timer which enters changes into the ISDN 
environment look-up table based upon receipt of entries before expiration 
of a time value entered into a change routine timer.

DESCRIPTION OF A PREFERRED EMBODIMENT 
Shown generally (10, FIG. 1) is a block diagram of a mobile radio (trunked 
dispatch) communication system. Included within the communication system 
is a resource controller (11) interconnected with a memory unit (12), an 
ISDN interface unit (20), an interconnect (27) interconnecting the ISDN 
interface unit (20) to a PSTN with an ISDN offering ISDN services, 
transceivers (13, 14, and 15), and a control transceiver (16). Also shown 
in FIG. 1 are communication units (17, 18, and 19) capable of 
communicating through transceivers (14-16). 
In one embodiment of the invention, the ISDN interface (20) is constructed 
as shown in FIG. 2 generally. Control of the ISDN interface is provided by 
an IBM-PC/XT (100) available from the IBM Corporation. Call control 
software (CCS) written for the IBM-PC/XT is as shown in Microfiche 
Appendix. An initialization procedure for start-up of the IBM-PC/XT is 
required upon activation of the IBM-PC/XT. 
Control of the interface between the ISDN interface (20) and the 
interconnect (27) to the PSTN/ISDN system (FIG. 1) is provided from within 
the IBM-PC/XT by a model #B100PC ISDN card (101) available from Telcos 
Communications, Inc., Eatontown, N.J. and installed within the IBM-PC/XT 
(100). 
The B100PC ISDN card (101, FIG. 2) is configured as shown in FIG. 3. 
Controlling software for the BP100PC ISDN card (101) is as provided by 
Telos Communications, Inc. The B100PC card (101) must be configured so 
that it's hardware interrupt and the start of it's I/O port address do not 
conflict with the other cards in the IBM-PC/XT (100). The location and 
settings of the B100PC (101, FIG. 2) I/O Base Address & DIP Switch panel 
(102, FIG. 3) and programming plugs (105 and 106), are as shown in FIG. 3. 
The positions of the five programming switches on the DIP switch panel 
(102) are as follows: the first switch (SW3) must be up, switches two 
through five (SW2, SW1, IRQ5 and IRQ3) must be down, and switch six (IRQ2) 
must be down. 
The B100PC ISDN card (101) supplied by Telos is designed for use with an 
audio signal from a PSTN telephone including telephone on/off hook control 
signals. Such signals are provided by a Pulsecom Voice Coupler (103). The 
model #1692-31 Pulsecorn Voice Coupler (103) provides the on/off hook 
control signals required for proper operation of the B100PC ISDN card 
(101) through use of a reed relay (not shown) controlled from a data ready 
control terminal of the RS232 port (not shown) on the IBM-PC/XT computer 
(100). The Pulsetom Voice Coupler (103) provides a voice interface between 
the resource controller (11, FIG. 1) and the ISDN interface (20, FIG. 1). 
Control signals between the resource controller (11, FIG. 1) and the ISDN 
interface (20, FIG. 1) are exchanged between a front end coprocessor (FEC) 
card (104) installed within the IBM-PC/XT (100) and the resource 
controller (11, FIG. 1). The FEC card (104) is a model #DCP-88/VM Persyst 
product manufactured by Emulex Corp. of Cosa Mesa, Calif. The FEC card 
(104) is configured as shown on FIG. 4 and uses software supplied with the 
FEC card (104). 
The FEC card (FIG. 4) must be configured as follows: serial line 1 set for 
DCE with jumpers in all locations on jumper panel E53-E72 and jumpers in 
the second and fourth position on jumper panel E45-E52, serial line 2 
remains at factory settings with jumpers present in the second and fourth 
positions of jumper panel E25-E33 and no jumpers on jumper panel E77-E78, 
serial line 3 remains at factory settings with jumpers present at 
left-center and bottom of jumper panel E17-E24 and no jumpers on jumper 
panel E73-E74, serial line 4 remains at factory settings of DTE with a 
jumper at fight-center and bottom of jumper panel E9-E16 and no jumper on 
jumper panel E75-E76, parallel printer port with no jumpers on jumper 
panel E1-E8, switches 1-4 for control register address remain at factory 
setting of 0x33c with switch 1 and 2 up and switches 3 and 4 down, 
switches 5-8 for shared memory segment address remain at factory setting 
of 0xD000 with switches 5,7, and 8 down and switch 6 up, interrupt level 
set for IRQ5 with a jumper to the fight on jumper panel E39-E43, 
transparent mode interrupt level set for IRQ4 with a jumper to the left on 
jumper panel E40-E4, and amount of memory set for 128K with a jumper on 
the top of jumper panel E35-E38. 
Control signals interfacing the resource controller (11) and the FEC card 
(104) within the IBM-PC/XT (100) are provided by call control software 
(CCS) (see Microfiche Appendix). Use of the CCS between the resource 
controller (11) and the FEC (104) within the IBM-PC/XT (100) allows the 
resource controller (11) to communicate with the ISDN interface (20, FIG. 
1) in the same manner as the resource controller (11) would communicate 
with a trunked console terminal (For an operational description of a 
trunked console terminal see Motorola publication #68-81063E20, published 
Sep. 15, 1989). 
To impose control by the CCS over the FEC card (104) and the B100PC card 
(101) an initialization routine must be used in conjunction with the CCS. 
The B100PC card (101) and FEC card (104) and their related software are 
initialized each time the IBM-PC/XT (100) is activated. The initialization 
is accomplished by a one time addition of the following lines to the 
autoexec.bat file: 
path c: ;c: dos;c: cmd;c: b100;c: dcp88 
set CM=c: b100 
netbios -i2 -p1 -ia000 -v5c 
bstart 
shell -ec: dcp88 -fD000 33c 5 
The command path c: ;c: dos;c: cmd;c: b100;c: adds the directories 
containing the B100PC and the FEC control commands to the command search 
algorithm. 
The command, set CM=c: b100 , informs the system where to look for the 
B100PC files. 
The command, netbios -i2 -p1 -ia000 -v5c, executes the B100PC NetBIOS 
emulation program. The options cause the FEC card (104) to use interrupt 
IRQ2, I/O port address of 0x100, shared memory start address of 0xa000, 
and software interrupt of 0x5c in communications with the NetBIOS 
emulator. 
The command, bstart, downloads the signalling procedures and activates 
operation of the B100PC card (101). The command shell, -ec: dcp88 -fD000 
33c 5, activates the FEC shell program. The options tell the shell to 
search the c: dcp88 directory for the d.sub.-- exec program, shared 
memory start address (0xD000), control register address (33c), and 
interrupt (IRQ5). 
Two new directories, c: b100 and c: dcp88, were created and the following 
programs were copied into the directories: 
c: b100 bstart/exe 
c: b100 netbios.exe 
c: b100 v120.sub.-- 1.exe 
c: b100 v120.sub.-- 2.exe 
c: dcp88 d.sub.-- exec.exe 
c: dcp88 shell.exe. 
In general to request service a communication unit (17, FIG. 1) transmits 
an inbound communication (23) on a radio frequency channel to the control 
receiver (16). The inbound communication may contain an ID number of the 
communication unit (17), a group number, and, upon occasion, auxiliary 
information such as a request for an interconnect with the PSTN. 
Upon receipt of the request for service in the form of an inbound 
communication (23, FIG. 1) from a communication unit (17) requesting to 
communicate with another communication unit (19) by the resource 
controller (11) through the control transceiver (16) the resource 
controller transmits an outbound signalling word (OSW) (21 and 22) to the 
requesting communication unit (17) and target unit (19) granting 
communication resources and identifying the frequency of such resources. 
The resource controller (11) also, simultaneously, allocates a transceiver 
(13) to service the communication transaction. The communication unit (17) 
and target unit (19) upon receiving the OSW (21 and 22) from the resource 
controller (11) tunes to the allocated frequencies and begins 
communicating. 
Alternately the target communication unit (19) may not be located in the 
same service coverage area as the requesting communication unit (17). 
Shown (FIG. 5) is an example of such a situation where the requesting 
communication unit (17) is located in cell 1 (served by a first 
communication system (10) generally designated by the reference numbers 
25) and the target communication unit (19) is located in cell 4 (served by 
a second communication system (10) generally designated by the reference 
number 26). An interface is provided between the resource controllers in 
cells 1 and 4 in the form of an ISDN communication link (31). 
Shown (FIG. 6) is a flow chart reflecting a method allowing access to 
targets located in other cells through use of an ISDN system. As shown 
(FIG. 6) all requests for target are processed by an ISDN interface to 
identify targets (55, FIG. 6) in remote locations. If a target is located 
in a remote location the control words allowing access to the remote 
target are recovered (56) from a routing table. The control words are then 
used to provide access to the remote target. 
In a situation involving a remote target (19, FIG. 5) communication unit 
(17) transmits an inbound communication (23) (51, FIG. 6) as in the 
previous example. The resource controller (11) as in the previous example 
receives the request through the control transceiver (16). The resource 
controller, in response, transmits an OSW (21) granting a resource for use 
by the requesting communication unit (17). OSWs originating within the 
resource controller (11) are also communicated to connected trunked 
console terminals as part of normal call control procedures. Since the 
ISDN interface (20, FIG. 1) is configured to act as a trunked console 
terminal the ISDN interface receives the OSW (54, FIG. 6). The OSW (21) is 
transmitted over a communication link between the resource controller (11) 
and the FEC (FIG. 2) within the ISDN interface (20). 
Contained within the CCS (FIG. 2) and associated memory within the 
IBM-PC/XT (100) is the location of potential target units (19). In this 
embodiment of the invention the CCS (FIG. 2) recognizes the OSW (21) as a 
request for access to a talk group call by the ID of the requested 
communication group contained within the OSW (21). The ISDN interface (20) 
refers to memory to locate (55, FIG. 6) target communication units (19) 
within the talk group located outside the requestor's cell (1, FIG. 5) and 
completes a connection based, at least in pan, upon an RF message link 
between the requesting communication unit (17 in cell 1, FIG. 5) and the 
target communication unit (19 in cell 4). 
Entry of locations of target communication units within memory of the ISDN 
interface may occur through manual entry on start-up of the ISDN interface 
or through a communication unit's automatic registration of location upon 
entry into a different cell and through transmission of location back to 
the home cell followed by subsequent storage of location in the ISDN 
interface memory. 
The locations of target communication units are stored within the ISDN 
interface memory (107) in the form of a routing table (108). Highest in 
the hierarchy of the routing table used to locate targets is a group ID 
number. Next highest are the ID numbers of communication units within 
particular groups. 
In one embodiment of the invention the inbound communication transmitted by 
a requesting communication unit (17) consists of a two word transmission. 
The first word of the inbound communication (23) contains the ID of the 
requesting communication unit (17). The second word of the inbound 
communication (23) may contain the group ID. 
The ISDN interface unit (20) uses the group number and the ID of the 
requesting communication unit (17) to identify a telephone number through 
which a target may be accessed from the routing table. The telephone 
number may be that of an ISDN interface associated with the resource 
controller of the target cell. The requesting resource controller may then 
access a target resource controller through the ISDN system and the 
telephone number listed within the routing table. 
The telephone number used to access the target resource controller may also 
be followed by a reference number used by the ISDN interface (20) located 
in the target cell (4) to identify the ID of a target communication unit 
(19) located within the target cell. The target ISDN interface (20) 
locates the target ID by using a routing table within the target ISDN 
interface (20). The routing table within the target ISDN interface (20) 
provides an ID number of the target. The ISDN interface (20) within the 
target cell (4) uses such target ID number to transmit an inbound 
communication to a resource controller (11) within the target cell (4) 
requesting access to the target communication unit (19). 
The ISDN interface (20) within the originating cell (1) in requesting 
access to a target communication unit (19) must transmit, in addition to 
the target telephone number, setup information into the ISDN network 
relative to the ISDN calling environment. The ISDN interface (20) accesses 
such information by recalling from memory ISDN call setup parameters from 
a look-up table within memory. The ISDN call setup parameters may be the 
same for all calls, or, may be changed to access different features within 
the ISDN network. Control of call setup features, in this embodiment, is 
under control of the CCS within the IBM-PC/XT. 
The purpose of the CCS, within the ISDN interface (20), is to monitor the 
calls and process the call requests, received either from the B100PC (101) 
or FEC cards (104, FIG. 2). The CCS originates several types of requests 
to the B100PC card (101) or to the FEC (104) based upon the message 
received. For example based on the type of OSW received, CCS places either 
a call origination or a call disconnect request to the B100PC card (101). 
Upon receipt of a channel grant OSW from the FEC (104), the CCS places a 
call origination request to the B100PC card (101). The B100PC card (101) 
sends a SETUP message to the ISDN system within the PSTN network. 
Following the SETUP message the originating ISDN interface (20) transmits 
the telephone number of the target ISDN interface (20). The target ISDN 
interface in addition to answering the telephone call subsequently uses a 
transmitted reference number to identify the ID of the target 
communication unit (19). The target ISDN interface (20) upon identifying 
the ID of the target communication unit (19) causes an inbound 
communication to be transmitted to the target resource controller (11) 
from the target ISDN interface (20) requesting access to the target 
communication unit (19). Upon receiving a response from the target 
communication unit (19) the target ISDN interface (20) transmits a CONNECT 
message back to the originating ISDN interface (20). 
Once the B100PC (101) receives the CONNECT message from the ISDN system, it 
passes control to the CCS. The CCS, in turn, sends an off hook signal to 
an asynchronous control board which, in turn, sends a signal to the voice 
coupler (103) through the data ready terminal of the RS232 port. Meantime, 
the B100PC card (101) opens a message path to the voice coupler (103) and 
sends a CONNECT ACK message to the ISDN system which ends the call 
initiation procedure. 
Audio is now exchanged between the originating communication unit (17) and 
target communication unit (19) in a normal manner until such time as the 
CCS receives an end of call (EOC) from the originating communication unit 
(17) or a call termination notice from the B100PC card (101). If the CCS 
receives a EOC from the originating communication unit (17) then the CCS 
transmits a terminate command to the B100PC card (101). If a terminate 
command is received from the B100PC card (101) the CCS transmits an EOC to 
the resource controller (11). 
In another embodiment of the invention, the operator may request service by 
activating a communication unit button labeled "PSTN interconnect". Upon 
activation of the PSTN interconnect the communication unit (17) transmits 
an inbound communication containing the ID of the communication unit (17) 
followed by a group ID number that when communicated to the ISDN interface 
(20) is interpreted as a request (23) for PSTN service. The resource 
controller (11) upon receipt of such a request (23) transmits an OSW (21) 
granting a resource and allocates a transceiver (13) as before. The 
resource controller then allocates a path between the transceiver (13) and 
the ISDN interface (20). 
Upon accessing the ISDN interface (20) the operator may enter a telephone 
number on the keypad of the communication unit (17) followed by activation 
of the send button. Upon receipt of the telephone number the ISDN 
interface may substitute the telephone number into an area of the routing 
table reserved for accessing PSTN subscribers under an ISDN environment. 
In such a case the telephone number becomes a part of the access code used 
by the ISDN interface. The ISDN interface may then execute the call under 
a then-current ISDN environment. 
After obtaining access to the ISDN interface, on the other hand, the 
operator may enter a request for modified ISDN services by accessing a 
call setup change routine program within the ISDN interface. The operator 
enters such request by entering a, for example, two digit number (token 
number) on the keypad on his communication unit (17) followed by the send 
button. Upon pressing the send button the communication unit (17) 
transmits an inbound communication (22) containing the token to the 
transceiver (13). The resource controller (11) receives the inbound 
communication (22) through the transceiver (13) and communicates the token 
word to the ISDN interface (20). The ISDN interface (20) upon receiving 
the token word executes the call setup change routine program and allows 
subsequent changes to the ISDN environment look-up table (109). The 
operator may then make such changes by entering characters and numbers on 
the keypad of the communication unit (17). 
Entry to the call setup change routine starts a timer from within the 
routine. Changes to the call setup table must be entered before expiration 
of a time entered into the timer. If the operator completes entry of 
changes and terminates the routine before expiration of the time period 
the changes are stored in a look-up table within the ISDN interface. Upon 
completing changes to the ISDN environment the operator terminates such 
routine by the entry of a second token number. 
In one embodiment of the invention the operator may also build his own 
unique look-up table for specific calling environments by entering a 
single digit token following entry to the call setup change routine. The 
unique calling environment may be later accessed by entering the identical 
single digit token before entering the target ID number or telephone 
number. 
In another embodiment of the invention control words specifying an ISDN 
environment are generated by an ISDN environment control program within 
the ISDN interface (20). The ISDN environment control program may generate 
specific environments in response to token words specifying an environment 
during call initiation. 
In another embodiment of the invention the ISDN interface is integrated 
into the resource controller (11). Integration of the ISDN interface into 
the resource controller would reduce data traffic between peripheral 
support devices at a resource controller base site. The integration of an 
ISDN interface into the resource controller may occur in the form of 
software additions (modem) and a hardware addition in the nature of a ISDN 
controller card similar to the B100PC card. In such a case the resource 
controller would execute interconnects directly upon receipt of inbound 
communications requesting such services through the use of subroutines 
(CCS) and the modem within the communication system resource controller.