SUBSCRIBER SERVICES ARRANGEMENT FOR MOBILE TELECOMMUNICATIONS SYSTEM PROVIDING PABX ACCESS

SERVICE D'ACCES A UN AUTOCOMMUTATEUR PRIVE POUR ABONNE DE SYSTEME DE TELECOMMUNICATION MOBILE

English Abstract

The invention relates to a subscriber services
arrangement in a telecommunications system which is utilized
by a plurality of mobile telephone stations, wherein at least
one private automatic branch exchange is intended to provide
PABX services to a predetermined group of subscribers of the
plurality of mobile telephone stations mentioned.

Claims

11

CLAIMS

1. A subscriber services arrangement (100) in a telecom-
munications system (MTN, PTN, PSTN), which includes a mobile
network (MTN) and a private telecommunications network (PTN),
wherein the subscriber services arrangement (100) includes a
first private automatic branch exchange (PABX1) which is
connected to the mobile network (MTN), wherein the subscriber
services arrangement (100) is also connected to a second
private automatic branch exchange (PABX2) in the private
network (PTN), wherein the second private automatic branch
exchange (PABX2) handles subscriber services for subscribers
(A3, MS3) in the private network (PTN), wherein a predeter-
mined group of mobile units (MS1, MS2) have arrangements for
connenction to the subscribers services arrangement (100)
irrespective of where these mobile subscribers are located in
the mobile network (MTN), so that said predetermined group of
mobile units (MS1, MS2) in the mobile telephone network (MTN)
are therewith included in the private network (PTN).

2. A subscriber services arrangement (100) in a telecom-
munications system (MTN, PTN, PSTN), which includes a private
telecommunications network (PTN) and a first mobile network
(MTNX) and a second mobile network (MTN), which mobile
networks comprises arrangement for connection with each
other, wherein the subscriber services arrangement (100)
includes a first private automatic branch exchange (PABX1)
which is connected tothe second mobile network (MTN), wherein
the subscriber services arrangement (100) is also connected
to a second private automatic branch exchange (PABX2) in the
private network (PTN), wherein the second private automatic
branch exchange (PABX2) handles subscriber services for
subscribers (A3, MS3) in the private network (PTN), wherein a
predetermined group of mobile units (MS2) in the first mobile
network (MTNX) have arrangements for connection to the
subscribers services arrangement (100) irrespective of where

12

these mobile subscribers are located in the mobile network
(MTNX), so that said predetermined group of mobile units (MS2)
in the first mobile telephone network (MTNX) are therewith
included in the private network (PTN).

3. An arrangement (100) according to Claim 1 or 2, which
comprises means for including the predetermined group of
mobile units in the number plan of the private network.

4. An arrangement (100) according to Claim 1, 2 or 3, which
comprises means for including the predetermined group of
mobile units to use the subscriber services of the private
network.

5. An arrangement (100) according to Claim 1, 2, 3 or 4,
wherein the arrangement comprises means for monitoring all
calls including a mobile telephone (MS2) with regard to
certain predetermined keyword set signals in the calls.

6. An arrangement (100) in a telecommunications system (MTN,
PTN, PSTN) according to Claim 1, 2, 3 or 4, wherein the
telecommunications system includes signal processing means
which enables transparent communication between the arran-
gement (100) and the mobile telephone (MS2).

7. An arrangement (100) in a telecommunications system (MTN,
PTN, PSTN) according to Claim 6, wherein the signal processing
means are arranged to use a standardized protocol for mobility


8. An arrangement in a telecommunications system (MTN, PTN,
PSTN) according to Claim 1, 2, 3, 4, 5, 6 or 7, which system
comprises an emulation device, so that the the function of the
first private automatc exchange (PABX1) can be emulated in the
system.

13

9. An arrangement according to Claim 8, wherein at least one
private automatic branch exchanqe is emulated in a mobile
services switching center (MSC1, MSC2) in the mobile telephone
network (MTN).

10. A method for handling a mobile unit (MS2) in a mobile
network (MTN) included in a telecommunication system (MTN,
PTN, PSTN), which mobile unit (MS2) is a subscriber in a
private telecommunications network (PTN) included in the
telecommunication system (MTN, PTN, PSTN), which system
comprises a subscriber services arrangement (100) connected
to the private telephone network (PTN), wherein the mobile
telephone network (MTN) includes a home location register
(HLR) in which the mobile unit is permanently registered as
belonging to the mobile telephone network (MTN), wherein the
mobile telephone network (MTN) includes a mobile services
switching centre (MSC1) which handles calls from the mobile
unit (MS2); and wherein the mobile services switching centre
(MSC1) is able to establish a connection with both the home
location register (HLR) and with said arrangement (100), said
method comprising the steps of:
- sending an activating message (1) from the mobile unit
(MS2) to the mobile services switching centre (MSC1);
- sending a subscriber data query (2) from the mobile
services switching centre (MSC1) to the home location register
(HLR);
- sending a subscriber data reply (3) from the home location
register (HLR) to the mobile services switching centre (MSC1),
said reply (3) pointing out the subscriber services arran-
gement (100);
- storing an arrangement address to the subscriber services
arrangement (100) in the mobile services switching centre
(MSC1).

11. A method according to claim 10, wherein the method
comprises the following additional steps:


14
- sending a first call signal (4) from the mobile unit (MS2)
to the mobile services switching centre (MSC1), said call
being intended for a unit, any unit, in the telecommunications
system (MTN, PTN, PSTN);
- restructuring the first call signal (4) to obtain a second
call signal (5) which includes the address of the subscriber
services arrangement (100); and
- directing, with the aid of said arrangement address, the
second call signal (5) to the subscriber services arrangement
(100),

12. A method for handling a mobile unit (MS2) in a first
mobile network (MTNX) included in a telecommunication system
(MTN, MTNX, PTN), which mobile unit (MS2) is a subscriber in
a private telecommunication network (PTN) included in the
telecommunication system, which system (MTN, MTNX, PTN)
comprises a subscriber services arrangement (100) in a second
mobile telephone network (MTN), wherein the subscriber
services arrangement (100) is connected to the private
telephone network (PTN) and the second mobile telephone
network (MTN) includes a home location register (HLR) in which
the mobile unit is permanently registered as belonging to the
said second mobile telephone network (MTN), wherein the first
mobile telephone network (MTNX) includes a mobile services
switching centre (MSCX) which handles calls from the mobile
unit (MS2), wherein the mobile services switching centre
(MSCX) is able to set-up a connection with both the home
location register (HLR) and with the subscriber services
arrangement (100) in the second mobile telephone network
(MTN), the method comprising the steps of:
- sending an activating message (11) from the mobile unit
(MS2) to the mobile services switching centre (MSCX);
- sending a subscriber data query (12) from the mobile
services switching center (MSCX) in the first mobile telephone
network (MTNX) to the home location register (HLR) in the
second mobile telephone network (MTN);



- sending a subscriber data reply (13) from the home location
register (HLR) in the second mobile telephone network (MTN) to
the mobile services switching centre (MSCX) in the first
mobile telephone network (MTNX), said reply (13) pointing out
the subscriber services arrangement (100);
- storing an arrangement address to the subscriber services
arrangement (100) in the mobile services switching centre
(MSCX) .

13. A method according to claim 12, wherein the method
comprises the following additional steps:
- sending a first call signal (14) from the mobile unit (MS2)
to the mobile services switching centre (MSCX) in the first
mobile telephone network, this call being intended for any
unit in the telecommunications system (MTN, PTN, PSTN);
- restructuring the first call signal (14) to obtain a second
call signal (15) which includes the address of the subscriber
services arrangement (100); and
- directing, with the aid of said arrangement address, the
second call signal (15) to the subscriber services arrangement
(100) in the second network (MTN).

14. A method in a telecommunication system (MTN, PTN, PSTN)
according to claim 10 or 12, which system (MTN, PTN, PSTN)
comprises a data storage device the data storage device
includes an address to the subscriber services arrangement
(100), said method comprising the additional steps of:
- sending a second subsciber data query from the mobile
services switching centre (MSC1, MSCX) to the data storage
device;
- sending a second subscriber data reply from the data storage
device to the mobile services switching centre (MSC1, MSCX),
which reply includes the address to the subscriber services
arrangement (100);

Description

W094~073 PCT/SE~/~381
213713~

rihPr serv~ r ~ L for ~bile
tPl~n~mic~ti ~ system provid~ PABX acoess.

TECHNICAL FIELD

The invention relates to a method and to an arrangement which
relate to a mobile telephone network which is utilized by a
plurality of mobile telephone stations. More particularly,
the invention relates toa telephone system subscriber service
arrangement and to a method of directing calls in a telephone
system.


BACKGROUND OF THE I~v~NllON

Historically, business telephone c~lh~cribers, i.e. employees
using a telephone at their office, have been using a statio-
nary private automated branch exchange (PABX) telephone. As
soon as such a subscriber leaves his office, any incoming call
has to be diverted to a secretary, a colleague etc.

With newer technology, a business telephone subscriber may
have a cordless telephone that makes him at least partially
reachable when he is away from his office.

The eu~vpean patent application EP 462 727 A2 describes how a
limited number of mobile telephone stations in a mobile -
telephone network are given access to business services-that~
normally only are available to the business telephone sub-
scribers using the private exchange (PABX). According to the
european application, only mobile stations located in a
limited area in the mobile network close to the private
exr~An~e are given access to the services. The application
does not explain how services can be accesc~ by mobile
stations located in a wide area.

WOs4n~ PCT/SE94/~81
2 ~13713~ ~-

Employees who need to make and receive telephone calls
wherever they are, have to use mobile telephone stations that
have no direct connection to a PABX.

Thus, the alternatives available today are to use either a
stationary PA8Xtelephoneora cordless telephone with limited
range of use, using a private numbering plan, or a mobile
telephone station with full mobility but with no PABX connec-
tion, using a public numbering plan.

In other words, with full mobility you lose business services
and communication possibilities that you normally have within
a PABX or within a private telecom network (PTN) comprising a
number of PA8Xs.


DISCLOSURE OF THE lNv~N~lON

The afG.~ -id problem to use business services of a private
telecom network and still maintain movability is solved in
accordance with the invention. One object of the present
invention is thus to enable a user of a mobile telephone in a
mobile telephone network to use subscriber services which are
normally only available to subscribers located in a private
telephone network. The intention of the invention is toenable
the user to avail himself/herself of the subscriber cervices
irrespective of where the mobile telephone is located in the
mobile network. This object is achieved with an inventive
arrangement which is connected to both the mobile telephone
network andto the private network, and by an inventive method
by means of which any call from the mobile telephone can be
directed to the inventive arrangement i-~e~ective of where
the mobile telephone is located in the mobile telephon~
network. Another additional object of the invention is to
enable use of services even if the user is located in a mobile
telephone network other than the one connected to the arran-


WO g4f2fiO73
PCr1SE94100381
3 ~13713(j

gement. This object is achieved by another inventive method bymeans of which any call can be directed to the inventive
arrangement. The advantage with the invention is that the
subscri~er can act as if he/she belongs to the private network
even if he/she is located in any of the mobile telephone
networks connected to the private network.


DESCRIPTION OF THE DRAWINGS

So that the invention will be more readily understood and
other features thereof made apparent, the invention will now
be described in more detail with referenceto the accompanying
drawings, in which

Figure 1 shows schematically a telephone system according to
the present invention and illustrates an inventive method of
directing a call from a mobile telephone to the inventive
arrangement; and

Figure 2 shows schematically a telephone system according to
t~e present invention and illustrates an inventive method of
directing a call from a mobile telephone in a first mobile
telephone network to the inventive arrangement in another
mobile telephone network.

DESCRIPTION OF ~KK~V EMBODIMENTS

.
Figure 1 illustrates a telephone system NIN, PTN, PSTN, which
includes a mobile telephone network PTN, a public telephone
network PSTN and a private telephone network PTN. The figure
schematically shows the mobile telephone network MTN with its
connections, on the one hand, to the publicswitched telephone
network PSTN and, on the other hand, to the private telecom
network PTN in accordance with the invention.

.1 Y4/ZW73
P~ Y4lw~Dl _
4 2137136

The mobile telephone network MTN is utilized by a plurality
of mobile telephone stations which in the figure are represen-
ted by mobile telephone stations MSl and MS2.

The mobile telephone station MSl is supposed to be used by a
normal mobile telephone subscriber using the mobile telephone
network MTN, while the mobile telephone station MS2 is used by
a subscriber belonging to the private telecom network PTN.

In the mobile telephone network ~TN, the mobile telephone
station MSl, in a conventiona manner, communicates by radio
with e.g. a base station BS which by e.g. a pulse code
modulation (PCM) link, is connected to a mobile ser~ices
switching center MSCl which in its turn is connected to the
public switched telephone network PSTN via another mobile
ser~ices swi~hin~ center MSC2. It is to be understood that
there can be a plurality of base stations and mobile services
switching centers in the mobile telephone network MTN.

Subscriber information about a subscriber using the mobile
telephone station MSl is stored, in a manner known per se, in
a home location register HLR connected to the mobile services
switching centers MSCl and MSC2.

Subscriber information about any subscriber belonging to the
private telecom network PTN, using the mobile telep~one
station MS2, is also stored in the home location register HIR
or in another data storage device (not shown) separated from
the home location register. - -

The private telecom network PTN is shown as comprising asingle pri~ate automatic branch exchange PABX2 to which a
plurality of stationary tele~hones (not shown) may be con-
nected. It is, however, to be understood that the private
telecom network PTN may comprise a number of PABXs and a
number of ~obile telephone stations MS2. It is also to be

Wo ~n~073 PCT~41~81
5 21~7~

understood that the private telecom network PTN not neces-
sarily must comprise the private automatic branch exchange
PABX2, but ~ay comprise just a number of mobile telephone
stations corresponding to MS2, served by the mobile telephone
network MTN.

In accordance with the invention, to provide PABX services to
the subscriber of the mobile telephone station MS2 of the same
nature as provided to the subscribers of the statio~ary
telephones connected to the private automated branch exchange
PABX2 in the private telecom network PTN, the mobile tel~rhone
network MTN comprises a subscriber services arrangement lO0
which includes a private automatic branch exchange PABXl.

Instead ofusing a physicalprivateautomatic branch exchange,
the functionality of a private automatic branch e~ch~n~e ~ay
be emulated, in software, in the mobile telephone networkMIN,
e.g. in a mobile services switching center such as MSC2. The
emulated private automatic branch exchange may, as an ~lter-
native, be located closer to the mobile telephone station MS2
in the mobile telephone network, e.g. in a base station
controller (not shown) controlling the base station BS.

By means of the private automatic branch exchange PABXl, it
will be possible to provide any requested PABX service to the
sllh~^riber of the mobile telephone station MS2.

To enable communication between the mobile telephone station
MS2 and subscribers in the private telecom network PTN, the
private automatic branch e~ch~n~e PABXl in the mobile tele-
- phone network MTN, will use an available connection, wired or
wireless trunks, to the private automatic branch eY~ ge
PABX2 in the private telecom network PTN.

The com~unication between the private automatic branch
exchanges PABXl and PABX2 may take place according to a

wog4~n PCTtSE94/~381
6 2137136

protocol DPNSS l, Q-SIG or any other protocol in a manner
known per se from interconnections between PABXs in private
telecom networks. DPNSS l and Q-SIG are the two standards
today to interconnect PABXs. DPNSS l stands for Digital
Private Network Signalling System No. l and Q-SIG refers to
the Q reference point in a digital access as specified by
C~

In the embodiment shown in the figure, in connection with a
set-up of a call from the mobile telephone station MS2, any
number dialled from that m~bile telephone statior. MS2 by a
subscriber who is a subscriber of the private telecom network
PTW shall be routed to the private automatic branch ~YrhAnge
PABXl. This is accomplished in that the network address of the
private automatic branch exchange PA8Xl is added as a prefix
to the dialled number by the mobile services switching center
MSCl, as controlled by the home location register HLR, before
the call set-up is sent on into the network. In the private
automatic branch exchange PABXl, the calling ct~h-criber's
mobile station integrated cervices digital number (MSISDN)
or directory number is translated into a pointer to his
service profile.

Figure l illustrates with the aid of arrows the signalling
required by an inventive method to direct a call from a mobile
telephone MS2 in the mobile telephone network ~TN to the
~h-criber service arrangement lOO. According to the inven-
tive method, the cAll is directed first to the subscriber
services arrangement lOO, irrespective of the tele~ho~e unit
in the telephone system MTN, PSTN, PTN for which the call is
intended. The method comprises the steps of:
- Transmitting an activating message from the mobile unit
(MS2) to the mobile services switching centre l. The mobile
services switching centre MSCl is referred to here as the
first mobile services switching centre l. The activating
message l is sent, for instance, in conjunction with the

Wos4n~ PCT/SE~/~381
7 ~137~ 3~ ~

mobile telephone MS2 first entering the cell area managed by
the first mobile services switching centre MSCl.
- Transmitting a subscriber data query 2 from ~he first
mobile services switching centre MSCl to t~e home location
S register HLR. The subscriber data guery 2 includes a request
for subscriber data for the mobile telephone MS2.
- Transmitting a subscriber data response 3 from the home
location register HLR to the mobile services switching centre
MSCl. The subscriber data response 3 includes an address to
the subscriber services arrangement lO0.
- Storing the subscriber response 3 in a register in the
mobile services switching centre MSCl.
- Sending a first call signal 4 from the mobile unit MS2 to
the mobile services switching centre MSCl. The call is
intended for a unit in the telephone system MTN, P~N, PSTN,
for example a unit A3. The unit for which the call is intende~
is unimportant to the inventive method.
- ~o~essing the first call signal 4 in the switching centre
MSCl to form a second call signal 5. This second call signal
includes the address of the subscriber services arrangement
lO0 after having been processed.
- Directing the second call signal S to the arrangement lO0
with the aid of the address, via a second mobile services
switching centre MSC2.

A call placed towards a subscriber of the private telecom
network PTN, using the mobile telephone station MS2, will be
passed on as already have been described above by the private
automatic branch exchange PABXl by using the subscriber's
MSISDN. A predetermined security analysis, e.g. in the home
location register HLR, will verify that only calls from the
private automatic branch exchange PABXl using the sub-
scriber'sNSISDN, willbeaccepted.Thehome locationregister
HLR will verify that the call comes from the private automatic
branch exchange PABXl by a predetermined analysis. If the

WO ~nbO73
~ vwo-
8 ~137~

result is positive, the call will proceed as a normal call to
an ordinary mobile telephone subscriber.

In principle, the below three alternatives can be identified
that will enable a subscriber to use his services in the
private automatic branch exchange PABXl:

1. ~he private automatic branch exchange PABXl will
monitor all calls to and from the mobile telephone stationNS2
for any Dual Tone Multiple Frequency (DTMF) signalling from
the mobile telephone station MS2.
Valid service codes signalled by using ~TMF, will be acted
upon in PABXl as specified according to a predetermined
specification.

Ifno call is establishedand the subscriberwants to
manipulatehis serviceprofile intheprivate automaticbranch
exchange PABXl, he can call a predetermined number and then
dial the service code that will be carried by in-band DTMF
signals.

2. Instead of using DTNF, it will be possible to useany
available me~hA~i~m in the mobïle telephone network
inorder to communicate between the mobile telephone
station MS2 and the private automatic branch ex-
change PABXl. An example of such a merhanism is the
Hobile Application Part (MAP) operation "Unstruc-
tured Supplementary Service Data" that is specified
inthe Global System forMobile communication ~GSM).

An advantage of the above mechanism is that it
enables the private automatic branch exchange PA~Xl
to communicate e.g. alerting messages to the mobile
telephone station MS2 by cenA ing text stringsto the
text window of the mobile telephone station. This is
not possible when alternative 1 above is used.

wos4nl~ PCTISE94l~81
9 ~ 3713~ ~

3. Another alternative to allow the subscriber to use
his services with no call active, is to dial a
service control sequence, and then push the send key
as for a normal GSM subscriber service. The private
automatic branch exchange PABX1 will receive the
service code in a call set-up messaged from the
mobile services switching center.

It will be obvious to one of normal skill in this art that the
method described with reference to Figure 1 can also be
applied when the mobile telephone MS2 is located in another
mobile telephone network MTNX, a so-called first mobile
telephone network MTNX different to the aforedescribed mobile
telephone network MTN, which in t~e exemplifying embodiment
is referred to as a second mobile telephone network MTN. This
embodiment is illustrated in Figure 2. The two networks MTNX
and MTN are handled by different operators. The first mobile
telephone network MTNX comprises a first mobile services
switrh;ng centre MSCX in whose cell area the mobile telephone
MS2 is located. An inventive method for directing a call, any
call, from the mobiletelephone MS2 to the subscriber services
arrangement 100 is illustrated in Figure 2 and comprises the
steps of:
- Transmitting an activating message 11 from the mobile unit
MS2 to the first mobile services switching centre MSCX.
- Sending a subscriber data query 12 from the mobile services
swi~c~ing centre MSCX in the first network MTNX to the home -
location register HLR in the second network MTN. - -
- Sending a subscriber data reply 13 from the home location
register HLR in the second network NTN to the first mobile
services switc-hin~ centre MSCX in the first network MTNX. The
subscriber data reply 13 includes an address to the earlier
mentioned data storage device. The data storage device
includes an address to the subscriber services arrangement
100 .

WO 9~/24073
~ 1 la~ O,
lo ~71~ ~

- Sending a second subsciber data query from the mobile
services switching centre MSCX to the data storage device.
- Sending a second subscriber data reply from the data storage
device to the mobile services switching centre MSCX. The
second reply includes the address to the subscriber services
arrangement 100.
- Storing the second reply in the first mobile services
switching centre MSCX.
- Sending a first call signal 14 from the mobile unit MS2 to
lo the mobile services switching centre MSCX. The call is
intended forany unit in the telephone system, for example the
unit A3.
- Processing the first call signal 14 to obtain a second call
signal 15 which includes the address to the subscriber
services arrangement 100.
- Directing the ~conA call signal 15 to the arrangement 100
in the ~?~on~ network MIN.

It is to be understood that the invention can be used for data
transmission. Another possibility is that the mobile tele-
phone contains an arrangement for switching off the automaticconnection to the subscriber service a~rangement 100.

The fact that PABX oriented services will be available to
subscribers of mobile telephone stations, will give mobile
telephony the following important merits:
It will be possible to use services which are not normally
available to a normal subscriber of a mobile te?ephone
station. These services include i.a. Intrusion (to allow
intrusion into an ongoing call, e.g. to ask an important
question or give important information) and Select Call
Acceptance (to allow certain numbers tocomplete callsso that
when the subscriber is at a meeting, a few important col-
leagues will ~e able to get through without letting all other
incoming calls be completed).

Representative Drawing