The present invention relates to an arrangement for combining at least two user services for the same user subscription of the type that is described in the preamble of patent claim 1.

A mobile telephone system that is based on digital technology, such as GSM (Global System for Mobile Communications), is used not only for vocal communication but also for computer services related to transferring of data. These computer services may either be telefax communication or other computer communication such as communication via a computing center. There is often an interchange between the conventional telephone network and the GSM system. Therefore, it is possible to send, for example, data from the GSM system to a station, such as a computing center that is connected to an analog communication network, such as the regular stationary telephone network.

A mobile telephone system that is based on digital technology, such as the GSM system, is digital all the way from the telephone to the central switching unit of the GSM network. Most of the stationary telephone network requires analog signals. The conversion to the analog signals is therefore done in a modem device that is connected to the switching unit of the digital system, when the communication is to be transmitted to the stationary network.

Computer calls are connected via a modem pool including many modems that is connected to the switching unit. The switching unit may determine that the incoming call is a computer call that is to be transmitted and is therefore able to switch the call to the modem pool, so that the call is connected to another modem that is connected to another computer. In this way, computer calls may be connected to the network.

When vocal calls are made from a telephone, to which no computer is connected, only the vocal calls are connected. Such a vocal call is not connected to

the system via a modem because the calls are connected directly to a line. The switching unit then determines that the call is not related to a computer but is vocal and the call is therefore not connected via the modem pool.

The problem is not the distinction made in the switching unit between transmitting data and vocal calls since a digital mobile communication system can make this distinction. The switching unit sends data and vocal calls via different interfaces, the modem pool or directly, respectively.

The problem rather occurs when calls come from the stationary network into its own switching unit for connecting a computer that is connected to the mobile communication system from another computer. The stationary telephone network cannot determine the difference between vocal calls and computer calls. As usually, the user telephone number to the user station connected to the digital com- munication system is dialed at the user station connected to the other computer. The modem is then automatically connected to the vocal channel, so that when the receiver at the receiving user station is lifted a sharp modem signal is heard. This means that there is a difference between vocal calls and computer calls.

One solution of this problem has earlier been for the user station receiving the call to have two user numbers, one for vocal calls and another for computer calls. A user is therefore assigned multiple user numbers of the user subscription. A display window at the user station may show "telephone call" if the user number for vocal calls is called, and "computer call" if the user number for computer calls is called, and data are transmitted to the user station.

There are systems available these days for transmitting telefax messages via mobile communication systems. The user has thus a special user number for this service. Telefax messages to the user are connected to a computer system connected to the GSM network. The messages are stored in a fax mailbox until the user calls a special telephone number and provides the computer system with a user number of a telefax machine to which the stored telefax messages

should be sent. If, as it is today, a computer service is added to the other services subscribed by the user, it means that the user has been assigned three user numbers to be used by the same user subscription.

These user numbers assigned to the user must be taken from the number series of the national number plan. It costs money to maintain these numbers. Companies who are involved in providing mobile communication services would like to be able to avoid these costs. It is desirable to provide as many and as varied services as possible at the lowest possible price. There is currently a limited amount of numbers available and the allocation of extra numbers is therefore restrictive.

This problem is a general problem of all digital networks.

One object of the present invention is to provide a device for digital communication networks where many different types of services can be obtained by users while using as few user numbers as possible. These user numbers are assigned to the user as number series of the stationary network with which the digital network may cooperate.

This object is achieved by the steps according to the appended patent claims.

The present invention is described in detail below with reference to the drawing wherein the figure shows a network arrangement for a mobile com¬ munication network connected to the general telephone network.

The figure shows a first user station A1 , that via an analog com¬ munication network 3, such as the public switched telephone network PSTN, is adapted to send either a vocal call or a computer call to another user station A2 that is connected to a mobile communication network 4, such as GSM.

The computer of A1 is connected to the analog stationary network 3. When computer calls are made from A1 , the modem M1 connected to the computer DS1 converts data to analog signals. This conversion is done by modulation on, for example, two carrier frequencies, one for "1" and one for "0" so that also computer calls, besides vocal calls, are transmitted analogically on the stationary network PSTN 3. An interface, (inter working function) IWF 5 is connected between the analog network 3 and the actual digital network 4. The interface 5 includes a modem pool 51 for computer calls and a unit 52 for analog/digital and digital/analog conversion of vocal calls between the networks 3 and 4.

Services related to vocal calls and computer calls must be assigned different user numbers because the stationary, analog network cannot distinguish between vocal calls and computer calls. The calls are sent between the units 3 and 5 as illustrated in the remaining portions of the figure. That is, the user inputs for computer calls is associated with the modem pool 51 and is separate from the user inputs for vocal calls.

The interface 5 is connected to the mobile services switching center MSC. Based on the user numbers, the switching center connects the calls as vocal calls or computer calls. The switching center MSC connects both vocal calls and computer calls via a base station controller BSC to a base transceiver station BTS. The base transceiver station BTS sends signals to and receives signals from the user station A2. In this way, computer calls to and from the computer DS2 are made via an interface M2 connectable to the mobile station MS2 of the user.

The present invention is based on the fact that extra identity numbers for the user may be obtained at almost no cost for mobile communication networks, such as the GSM network. In a user register (not shown) within the GSM network, the user is assigned a user number that is outside the number series of the operator. For simplicity, the description of the present invention will refer to the GSM network from here and on although the present invention is applicable to other digital mobile communication networks.

According to the present invention, a service unit 1 , preferably a computer unit 1 such as a computering center, is connected to the analog network 3 via an interface 2. The interface 2 may be part of the interface 5 and includes a modem pool 21. The service unit 1 has an inquiry unit 11 so that when calls are coming into the service unit, the requiry unit asks questions to the caller before the user station is connected. According to the present invention, it is therefore possible for a user to have many different services on the same user subscription, such as services related to vocal calls, computer calls, telefax etc. The service unit is a complement to handle these services.

The invention may have two embodiments:

1. All the extra services are assigned a special service user number in the public telephone network. The service unit 1 has a data base 12 in which user numbers, or other suitable user identifications, are stored for users utilizing the extra services. The user numbers are stored together with virtual user numbers assigned to every user service that is subscribed to within the GSM network. It is not necessary for the user to know about the virtual user numbers. When the special service user number is called to, the requiry unit 11 asks a question regarding the ordinary user number of the user and/or some other suitable user identification, for example, the user's name or a code created by the user etc. and the particular service which is requested.

The virtual user number for the particular service requested by the user is found. The service is thereafter connected with the virtual user number within the GSM network and via the modem in the modem pool 21 that the computer call was connected to.

2. A special service user number within the public telephone network is established for every extra service. Every service user number is common for all the users of the GSM system. Every such service user number is to be connected to the service unit 1. The service unit has a data base for each extra service in which the

user number, or other suitable user identification, for users requesting the service are stored together with a virtual user number for the service. This storage is done for each individual user within the GSM network. It is not necessary for the user to know about the virtual user numbers. When the special service user number is called to, the service unit asks a question regarding the ordinary user number of the user or some other suitable user identification. This information may nowadays be obtained automatically via the stationary network. The service is then connected with the virtual user number within the GSM network 4 and then via the modem in the modem pool 21 to which the call was connected to.

The connection from the service unit to the GSM network may be done via the ordinary modem pool 51 (shown as a dashed line), or in the alternative the service unit 1 may arrange the data (shown as a solid line) as if the data came from the modem pool 51 and send the signal directly to the mobile switching center MSC of the network.

The network then connects the computer calls. If the computer is not turned on, this is indicated to the user connected to the user station that is nearest the base transceiver station BTS. This information is sent back via the GSM network to the service unit 1. This unit is preferably equipped with a data base 13 for temporary storage of the data sent by the user A1. In addition, a message is preferably sent to the so called SMS service unit. The SMS unit sends a text message to the user A2 via the switching center MSC of the network and the base transceiver station BTS. This message is sent to the ordinary identification number of A2 within the GSM network to show on a display window on the user's mobile telephone that "You have received computer mail" or a similar message. Then the user knows that he should turn on the computer by, for example, connecting it to the telephone and then call the service unit and retrieve the data stored therein. In the alternative, the computer can in another place A2' possibly be connected to another user station. The service unit is then called and the stored data is retrieved.

Obviously code numbers must exist so that only authorized persons retrieve the data stored in the central unit.

When the computer calls are derived from user stations connected to the digital network, a call may be identified as being a computer call by the intelligent mobile switching center MSC. This center feeds the signal directly to the modem pool 51 to be forwarded with the user number of the user station A1 to its computer DS1 via the modem M1. The user A1 may either have a separate user number for the user's computer DS1 or have a common user number for vocal calls and computer calls and a user switching unit AV that identifies the type of incoming calls.

It is also possible that the computer of the user A1 is not connected or the line of the user is busy. The network 4 may then via the intelligent mobile switching center MSC connect the outgoing call to the service unit 1 to be stored there. The requiry and message unit 11 of the service unit may be adapted to determine the condition of the user A1 intermittently and inform the user that the computer call is stored in the unit. The user may also be informed about how to retrieve the call as soon as the user A1 can be reached. It is obvious that this possibility also applies to computer calls to users both within and outside the digital network.

The service unit that is described above stores the virtual user numbers for some of the services of the user. It is obviously within the scope of the present invention to store the virtual numbers for all the services of a user. That is, even vocal calls are stored in a service unit and only one number of the number series of the stationary network is used.

Many modifications are possible within the scope of the attached patent claims.