Background With the introduction of Internet-related services the use of telecommunications services has changed noticeably in recent years. The Public Services Telephone Network (PSTN) and ISDN lines are being used to an increasing degree for data communication, for example for interactive communication with the world wide web, or for downloading data files. On ordinary telephone lines, these operations may take several hours, during which the telephone lines will be occupied.

For large companies, dedicated leased lines constitute a flexible and cost effective solution to this problem. For smaller companies and for individuals this will not be feasible because of the relatively high cost. For these user categories, PSTN telephone lines or ISDN connections may be the only realistic solution.

An ISDN connection offers three channels on the same physical link: two circuit switched B channels of 64kbit/s each for dial-up access for data or speech connections and one packet switched D channel. The total bandwidth of the D channel is 16 kbit/s, but the effective capacity for control information or data is 9.6 kbit/s. A protocol known as LAPD (Link Access Procedure for D channel) is used for communication on the D channel.

However there is a desire to be able to search for or retrieve information from the Internet, non-interactively, on a 24 hour basis. With an ordinary telephone connection, this would mean that the connection was constantly occupied, and also the cost would become prohibitively large. Using one B channel of an ISDN connection as a permanent connection would also be expensive in the long run.

Summary of the Invention It is an object of the present invention to provide a permanent connection for Internet Protocol (IP) traffic at a reasonable cost.

It is another object of the present invention to provide a permanent low speed connection for IP traffic based on the ISDN protocol, which will be available to all ISDN subscribers.

These objects are achieved according to the invention by adding software and hardware to the ISDN control computer, which permits the use of the D channel of an ISDN connection as a permanent connection to the Internet and performs searches automatically on a 24 hour basis. The subscriber may specify a search profile. When information is changed, or when the requested information is found, the subscriber is notified.

The solution according to the invention offers the following advantages: - A flexible Internet search tool based on the standard ISDN interface may be implemented at a reasonable cost.

- The user can control the quality of service by selecting the bandwidth of the IP channel.

- The user does not need to spend time searching for the information; - The user is informed when information changes, or when the desired information is found, whether this takes place at regular or irregular time intervals; - The bandwidth requirements are reduced when the search is not interactive. Thus the cost is reduced, allowing a 24 hour a day search.

- The solution enables the integration and interaction of voice, video and data services.

- The solution enables the ISDN subscriber to act as a server, and thereby content provider in a data network, and to receive e-mail directly to the ISDN terminal.

Brief Description of the Drawings Figure 1 illustrates schematically the connection from the ISDN subscriber via the ISDN network to the Internet according to the invention; Figure 2 illustrates the connection from the ISDN subscriber via the ISDN network to the Internet in more detail; Figure 3 is a flow chart of the actions required to install and activate the services according to the invention; Figure 4 is a flow chart of the actions required to connect to the Internet according to the invention; and Figure 5 is a flow chart of the actions required to specify the search profile and the conditions for notification when the conditions are met.

Detailed Description of Embodiments Figure 1 shows an ISDN connection to a computer network for retrieving data according to the invention. In a preferred embodiment, the computer network is the Internet, but similar connections may be set up to any computer network, for example a network which allows an X.25 or Internet Protocol (IP) connection. An enhanced ISDN terminal known as a PMMX (Personal Multimedia Exchange) 1 is connected to an ISDN exchange 3. The ISDN exchange is connected via an Internet access server 5 to the computer network 7. Other servers 9 are connected to the data network as well.

The PMMX is a workstation, a PC or a local router, configured as described in connection with Figure 3.

The PMMX does not have a fixed IP address, but obtains an IP address from the IP handler each time a connection is set up. The IP address is returned each time a connection is ended.

The PMMX contains a user interface for the handling of the three ISDN channels and for handling operation and maintenance functions in the network, and also contains functions for utilizing the IP interface included in the Personal Computer (PC), workstation or router used.

A user may log in to the PMMX with a user identity and a password, or in any other way known in the alt, for example with voice recognition.

Figure 2 shows the connection from a subscribers PMMX 1' to a data network, which in this embodiment in the Internet 7' in more detail. As before, the PMMX is used to handle the two B channels and the D channel of an ISDN connection. The PMMX 1' is connected to an ISDN network 11, comprising at least one ISDN exchange.

The ISDN network 11 is in turn connected via a 2 Mbit/s PRI (Primary Rate Interface) to an ISDN router 13 for connecting the two B channels to the Internet 7'.

The ISDN network 11 is also connected via a PHI (Packet Handler Interface) to a packet handler 15, which may be an ordinary packet handler used as a gateway to an X.25 network 17. The packet handler is connected via an interface I1 to a D channel router 19 for connection to the Internet 7'. The connection from the ISDN network 11 via the packet handler 15 and the D channel router 19 is used for the data transmission on the D channel. It will be obvious to the skilled person that the ISDN router and the D channel router may be implemented as one unit.

The ISDN router 13 and the D channel router 19 are connected via an Ethernet connection 21 to a router 23, which is connected to the data network 7', and connection means 25 for authentication of the user and activation of the IP address and other IP parameters. For an Internet connection, the means 25 will comprise a Dynamic Host Configuration Protocol (DHCP) server, a Remote Authentication Dial-in User Service (RADIUS) and a Domain Name Server (DNS) 25.

The ISDN router 13, the D channel router 19, the router 23 and the connection means 25 constitute the Internet packet handler IPH. For connection to another data network than the Internet, the router 23 and the connection means 25 would have to be adapted to this kind of data network.

In this way, the D channel may be used as a permanent connection to any data network, for example, the Internet. However, this channel is also needed to control the use of the two B channels. This is solved by utilizing the fact that the D channel is a packet switched channel, with a well defined protocol: the LAPD (Link Access Procedure for channel D). The ability to use the D channel for transfer of user data is defined in the ISDN standard X.3 1.

The header information in each packet transmitted on the D channel includes, in the Service Access Point Identifier (SAPI) field, information about the type of information included, according to the LAPD protocol. Control information for the B channels is denoted "0" in the SAPI field. Data communication, for example with the Internet, which should simply be transmitted through the ISDN exchanges, is denoted "16" in the SAPI field.

In a preferred embodiment, the connection between the PMMX and the packet handler is set up by dialling the number of the packet handler. Then all packets intended for the packet handler are marked with "16" in the SAPI field, so that they will be transmitted through the telephone network 11 directly to the packet handler.

In another embodiment, certain major networks, such as the Internet, may be identified by individual digits in the LAPD protocol. For example, data packets intended for the Internet might be identified by the digit "17", which is currently not used in the LAPD protocol. In this embodiment it would not be necessary establish a connection to a packet handler; all cells with the digit "17" in the SAPI field would automatically be transmitted to the data network.

In this way, the channel may be used for data communication and then, when the need arises, for control information about the B channels, by including one or more data packets identified as intended for the switch, while still maintaining the data connection to the Internet, as shown in figure 1.

Figure 3 is a flow chart of the actions to be taken to install the PMMX software.

Step 100: The ISDN terminal is installed and configured in the way common in the art.

Step 102: The additional software and hardware needed in the PMMX is installed.

Step 104: The PMMX monitor, which is the management application used to control the function of the ISDN is installed.

Figure 4 is a flowchart of the actions to be taken when a subscriber wishes to connect and log in to the Internet according to the invention.

Step 110: The user initiates the connection to the Internet Packet Handler (IPH).

This will normally be done by clicking on an icon on the computer screen, or by entering a command through the user interface, which will initiate the dialling of the number to the packet handler.

Step 112: The connection procedure is performed over the D channel to the IPH using X.3 1 specifications.

Step 114: The user identifies himself by entering the appropriate user identity and password. The user identity and the password may be stored on any medium, such as a smart card or a data file, or it may be typed by the user.

Step 116: When the connection between the PMMX and the IPH has been set up, the control protocol negotiation will be performed to establish a connection of the desired bandwidth.

Step 118: User authentication is carried out by the connection means 25, based on the identification offered in step 114.

Step 120: The PMMX requests the necessary parameters.

When connecting to an IP (Internet Protocol) network, this request is based on the Request for Comment (RFC) concerning DHCP.

At least the following parameters are requested and updated from the IPH-DHCP server: - IP address - IP subnetmask - Gateway IP address - DNS address Step 122: The connection between the PMMX and the Internet is set up.

In step 116, the de facto standard protocol today for use together with the IP is Point-to-Point Protocol (PPP). This also enables the authorization in step 118 to be carried out by the connection means 25.

Figure 5 is a flow chart of the actions to be taken when the search profile, and actions to be taken when the conditions are met, are to be specified. The connection between the PMMX and the data network must be set up first, as described in figure 4.

Step 130: The subscriber specifies the conditions to be fulfilled by the search.

Step 132: The subscriber specifies if any actions should be taken when the conditions are met in the search, for example when a specified item is advertised for sale at a price lower than a specified price, for example, if an e-mail should be sent to the vendor to order the item.

Step 134: The subscriber specifies the way in which he wishes to be notified. The notification may be sent to the user in a number of different ways: - The PMMX may call the user's fixed or mobile phone, or one of the B channels in the ISDN connection, and inform via a voice message.

- The PMMX may send a message to the user's pager.

- The PMMX may send an e-mail to the user, at any location, for example, at work.

Step 136: The subscriber specifies any other restrictions to the notification, for example, no phone notification between 11pom and 7am.

It is also possible to specify actions to be taken once a specific condition is met. For example, a product or a service may be ordered automatically once the conditions are favourable. Selling or buying orders on the stock exchange may be initiated. In such cases, the PMMX informs the user that the condition is met and asks if the action should be carried out, or simply informs the user that the action has been carried out.