Abstract:
A mobile telephone is easy to carry around but has a small keypad and a small display. A normal deskphone has a big keypad and display and has a convenient handset, but is stationary. A stationary communications terminal is described which is connected to a mobile telephony network via a mobile telephone. The mobile and the stationary terminal have each a BLUETOOTH radio transceiver and are interconnected via a BLUETOOTH link. The stationary communications terminal lacks identity in the mobile network. A subscriber, owning the mobile, can call on the stationary communications terminal and can move to another network having another stationary terminal, on which he can make a call. Another subscriber with a mobile can call on the communications stationary terminal. To prevent misuse the subscribers take an authentication code for his respective mobile on the stationary terminal, and the authentication can be made valid for a predetermined period by taking a service code.

Description:
This application is a continuation application of U.S. Ser. No. 09/898,480, filed on Jul. 5, 2001, now U.S. Pat. No. 7,792,484, the entire content of which is hereby incorporated by reference in this application. 
    
    
     TECHNICAL FIELD 
     The technical field relates to an arrangement and a method in a telephony system in which a stationary telephony terminal is connected to a mobile radio telephony network via a mobile radio telephone, and to the stationary telephony terminal. 
     BACKGROUND 
     A person communicating via a telecommunications network often uses a conventional stationary deskphone, which is convenient to use as it has a big keypad and a big display. The person can use stationary deskphones when moving between different locations, but then subscriptions, rights, identities etc belonging to other persons are utilized. Instead, when moving the person can use a mobile telephone, which is small and is easy to carry around. The mobile telephone on the other hand has a small keypad that can be a bit difficult to use and has a tiny display that can be hard to view. The sound quality and the volume are not always excellent for a mobile telephone but are nearly always so for a deskphone. The handset for the deskphone is often regarded as more convenient to hold than the small mobile telephone. This leads to a situation where people have both a mobile telephone to carry around and a stationary deskphone in the office. The person has separate accesses although one would have been enough and the person also must have multiple sets of user data in the telephony system. Multiple directory numbers can be confusing for other persons. Also, the deskphone still requires the person to be tied to a particular telephone line, and if the person moves permanently the user data have to be changed. 
     The European patent application EP 0 930 766 A2 discloses a system for radio communication between a wireless LAN and a PBX. The wireless LAN has remote devices, which have radio access to the PBX and can use its different features. In an embodiment the remote device is a cash register which is cable connected to a mobile phone. The latter is in turn radio connected to the PBX. In an alternative the phone is a wireless phone which communicates with the cash register by digital radio communication. 
     In the U.S. Pat. No. 5,726,984 is disclosed a communication system including a LAN, which has radio access points. Computing devices are in radio contact with the access points and peripheral devices, such as printers, are radio connected to the computing devices. The patent also discloses stationary telephones which are wire connected to radio access devices. The latter are in turn radio connected to the LAN, which is a wired backbone LAN. 
     SUMMARY 
     A main problem is that a mobile radio telephone, which is easy to carry around can be a bit inconvenient to handle, while a more convenient desk telephone is stationary. This leads to a situation where people have both a stationary desk telephone and a mobile radio telephone, which requires multiple sets of user data in the telephony system for one person and also requires the person to have multiple directory numbers. 
     A further problem is that if the person moves permanently the person&#39;s user data in the telephony system have to be changed. 
     Still a problem is that if the person prefers to use different stationary telephones when traveling around, other persons telephones and rights connected to those telephones must often be utilised. 
     The above problems are solved by a stationary telephony or communications terminal, which a subscriber connects to a mobile radio telephony network via the subscriber&#39;s mobile radio telephone. The stationary telephony terminal and the mobile radio telephone are connected to each other by a wireless short range communication link. The mobile radio telephone can move and connect different stationary telephony terminals on different locations. The stationary telephony terminals have no own telephone number or other identity in the mobile radio telephony network. 
     The stationary communications terminal and the mobile radio telephone have each a short range transceiver for the wireless short range link. The stationary communications terminal is made to be as convenient to use as a conventional deskphone. When the mobile radio telephone is in its standby mode and is in range of the wireless short range link of the stationary communications terminal, and before a call is made or answered on the stationary terminal, they perform an identification procedure via the short range link. Outgoing calls can thus be set up and incoming calls can be taken on the stationary terminal. 
     In an example embodiment the mobile telephone sends an identification, e.g., its telephone number, to the stationary terminal. Before a subscriber keys for a call on the stationary terminal an authorization must be given, e.g., the PIN-code for the subscriber&#39;s mobile telephone. 
     A purpose with the technology described herein is that a subscriber shall have access to a mobile radio telephone, that is easy to carry around, and also have access to a convenient telephony terminal on different locations. 
     Another purpose is that the subscriber shall have only one telephone number. 
     Still a purpose is that there shall be only one set of user data for the subscriber in the network. 
     Yet another purpose is that when the subscriber moves permanently, the set of user data for the subscriber in the network shall remain unchanged. 
     A purpose is also that the owner of a mobile radio telephone shall be able to prevent others to use his mobile telephone via a stationary telephony terminal. 
     An advantage with the technology described herein is that the subscriber has a mobile telephone that is easy to carry around and also has access to a convenient telephony terminal on different locations. 
     Another advantage is that the subscriber needs to have only one telephone number. 
     Still an advantage is that the subscriber can have access to a convenient telephony terminal on different locations but can avoid to use other persons subscriptions. 
     Yet another advantage is that the subscriber has access to a convenient telephony terminal and at the same time the set of user data in the network can remain unchanged and no wiring changes are to be made when the subscriber moves permanently. 
     An advantage is also that the system of the stationary telephony terminal and the mobile can be made safe to prevent illegitimate use of a mobile telephone via the stationary terminal. 
     The technology will now be further described with the aid of preferred, non-limiting, and example embodiments in connection with enclosed figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a view over a telephony system; 
         FIG. 2  shows a block diagram over a stationary telephony terminal; 
         FIG. 3  shows a block diagram over a mobile telephone; 
         FIG. 4  is a signalling diagram for a first discovery phase; 
         FIG. 5  is a signalling diagram for an incoming call to the mobile telephone/stationary telephony terminal; 
         FIG. 6  is a signalling diagram for call release from the stationary terminal; 
         FIG. 7  is a signalling diagram for call release from a subscriber having a call to the stationary terminal; 
         FIG. 8  is a signalling diagam for setting up a call from the stationary telephony terminal; 
         FIG. 9  is a signalling diagram for a first authentication procedure; 
         FIG. 10  is a signalling diagram for a second discovery phase; 
         FIG. 11  is a signalling diagram for a second authentication procedure; 
         FIG. 12  is a flow chart over the first discovery phase; 
         FIG. 13  is a flow chart over the second discover phase; and 
         FIG. 14  is a flow chart over the first authentication procedure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a survey of a telephony system TS 1  with an example embodiment. A first mobile radio telephone M 1 , having a phone number Ph 1 , is connected to a first mobile radio telephony network MTN 1  via a radio link R 1  to a radio base station BS 1 . This station belongs to the first mobile telephony network. A subscriber telephone S 2  is connected to a public telephony network PSTN 1 , which in turn is connected to the mobile telephony network MTN 1 . The mobile telephone M 1  communicates with an inventive stationary telephony or communications terminal S 1  via a short range wireless link SWL 1 . In the example embodiment, the wireless link SWL 1  is a short range BLUETOOTH radio link between BLUETOOTH transceivers, of which a first transceiver BT 1  is connected to the mobile telephone M 1  and a second transceiver BT 2  is connected to the stationary telephony terminal S 1 . A second mobile radio telephone M 3 , owned by a subscriber P 3 , is within the area of the first mobile radio telephony network MTN 1 . A second mobile radio telephony network MTN 2  has a second radio base station BS 2 , which is connected to the public telephony network PSTN. A second stationary telephony terminal S 3 , which is placed on a complete different location than the stationary terminal S 1 , is within a cell covered by the base station BS 2  and has a BLUETOOTH transceiver BT 3 . 
     In  FIG. 1 , for the sake of simplicity, the mobile telephony network MTN 1  is shown with the only base station BS 1 . The network is a common mobile network with several base stations, mobile switching centres, gateways and the like, not shown in the figure. 
     The stationary terminal S 1  has similarities with a conventional stationary deskphone in that it has a telephone body  1 , a handset  2  and is provided with a keyset  3  and a display  4 . As an alternative to the keyset  3  it also has a device  3   a  for voice command. The terminal S 1  differs from the conventional deskphone in that it lacks a wire for connection to a telephony network but has only a power cord  5  connected to a conventional power socket. The stationary terminal S 1  also differs from the conventional deskphone in that it has the abovementioned BLUETOOTH transceiver BT 2  and in that it lacks an own telephone number. The second stationary telephony terminal S 3  is similar to the terminal S 1  and functions in the same manner. The stationary terminal S 1  will be described more in detail below. 
     The BLUETOOTH transmission is specified in the BLUETOOTH Specification 1.1. In short BLUETOOTH works in the following manner. BLUETOOTH is a frequecy hopping system with 79 fequencies within a band and with 1600 frequency hops per second. The hops follow a pseudo random hop sequence. Each BLUETOOTH device has a 48-bit IEEE address determined by a manufacturer number and a consecutive number and the hop sequence for a BLUETOOTH device is determined by applying an algorithm on the address. Each BLUETOOTH device has an own clock time and if this time and the address is known it is possible to go directly into the hop sequence for a certain BLUETOOTH device and follow it. The communication between BLUETOOTH devices is organized with a master and one or more slaves forming a pico network, in which the hop sequence is determined by the master. 
     A BLUETOOTH device can search another BLUETOOTH device by making either a page or an inquiry. In case of page the address of the sought BLUETOOTH device is known to the searching device and in case of inquiry the address is unknown and the sought BLUETOOTH device can be any device. The BLUETOOTH devices listen on 32 different frequencies, about one second for each frequency. A paging BLUETOOTH device sends the address of the sought device, rapidly changing between all 32 frequencies, and will hit the sought device. An inquiring BLUETOOTH device sends a certain code in stead of the address, rapidly changing frequency. A listening device that hears this code responds with its address and clock time. The entire BLUETOOTH specification may be found on the web under. 
     In brief the stationary terminal S 1  is used in the following manner. A subscriber P 1 , who owns the mobile telephone M 1 , visits a room with the stationary telephony terminal S 1 . The mobile M 1  has established contact with the mobile network MTN 1  via the link R 1  and is in its standby position. The subscriber P 1  wants to call the telephone S 2  and prefers to use the stationary terminal S 1 , because it has the keyset  3  that is big and easy to use, the display  4  that is big and easy to view and the convenient handset  2 . The subscriber lifts the handset  2  and keys the number to the telephone S 2  on the keypad  3 . A channel on the BLUETOOTH link SWL 1  is set up to the mobile telephone M 1 , which initiates the mobile to switch to its active mode. A channel on the radio link R 1  between the base station BS 1  and the mobile telephone M 1  is set up and the telephone S 2  is then called via the mobile network MTN 1  and the public network PSTN 1  in conventional manner. A subscriber P 2  takes the call on the telephone S 2  and a conversation can take place. 
     When the subscriber P 2  wants to call the subscriber P 1 , he dials the number to the mobile telephone M 1  on his telephone S 2 . The call is coupled through the public network PSTN 1  and the mobile network MIN 1  to the base station BS 1 , through which a channel on the radio link R 1  is set up to the mobile telephone M 1 . The mobile telephone is initiated to call the stationary terminal S 1  via the short range link SWL 1 . The stationary deskphone generates a ringtone, the subscriber P 1  lifts the handset  2  and a conversation between the subscibers P 1  and P 2  can take place. 
     to The subscriber M 1  can bring the mobile radio telephone M 1  along and move to the location for the second stationary telephony terminal S 3 . There telephony calls can be set up via the stationary terminal S 3  and also incoming calls to the mobile M 1  can be taken on the terminal S 3  in the same way as for the stationary terminal S 1 . 
       FIG. 2  is a block diagram showing the stationary telephony terminal S 1 . The latter has a processing unit  6  which is connected to the keyset  3  and the display  4 . The processing unit is also connected to an analog-digital converter  7  and to a unit  9  with a hook function. The analog-digital converter is connected to an amplifier  8  for a loudspeaker or microphone function and to the handset  2 , which actuates the hook function  9 . The BLUETOOTH transceiver BT 2  is connected to the processing unit  6  and is also connected to the analog-digital converter  7  an has an antenna  10  for the short range link SWL 1 . The transceiver BT 2  has also a direct connection  11   a , past the processing unit  6 , for exchaning speech signals with the converter  7 . A bell  11  is connected to the processor  6 . The display  4  is a conventional one and is controled by the processing unit  6 . Telephone numbers are keyed on the keyset  3 , which also is used to key codes for programming the functions of the processor  6 , as will be discussed later. The unit  9  has a common hook function, which indicates hook-on or hook-off position of the handset  2  and actuates the processor  6 . The handset  2  is a common one with microphone and loudspeaker. Also the amplifier  8  is a common one for processing speech signals when the telephony terminal S 1  is set in a loudspeaking position. The converter  7  converts speech signals analog-to-digital and digital-to-analog in conventional manner. The BLUETOOTH transceiver BT 2 , having a BLUETOOTH device address BE 2 , transmits and receives speech and signalling information on the link SWL 1 . When a telephone number is keyed on the keypad  3 , the number is processed in the processor  6  and corresponding signals are sent by the trasceiver BT 2  to the trasceiver BT 1  in the mobile telephone M 1 . Speech signals via e.g., the handset  2  are transceived by the transceiver BT 2 . For an incoming call to the mobile telephone M 1  and the stationary terminal S 1  the transceiver BT 2  receives a ring initiating signal, which initiates the processor to generate a ring signal on the bell  11 . In an alternative embodiment the stationary terminal is used so that it is the mobile that is ringing while the call still can be taken on the terminal. 
       FIG. 3  is a block diagram showing the mobile telephone M 1 . The mobile has a processing unit  16  which is connected to a keyset  13  and a display  14 . The processing unit  16  is also connected to an analog-digital converter  17  which in turn is connected to a microphone and a loudspeaker. A bell  21  is connected to the processing unit. The mobile phone also has a radio circuit unit  19  which is connected to the processing unit  16  and has an antenna  20  for the radio link R 1 . The BLUETOOTH transceiver BT 1  is connected to the processing unit  16  and has an antenna  12  for the short range link SWL 1 . The transceiver BT 1  has a direct connection  22  to the converter  17  and a direct connection  23  to the radio unit  19 . The direct connections  22  and  23  are used for exchange of speech signals past the processing unit  16 . The processing unit  16  is loaded with software  15 . The display  14  is a conventional one and is controlled by the processing unit. The keyset  13  is also conventional and is used to key telephone numbers, control menus on the display etc. The radio circuit unit  19  transmits and receives radio signals in conventional manner and the analog-digital converter  17  converts speech signals, also in conventional manner. The BLUETOOTH transceiver BT 1  transmits and receives speech and signalling information on the link SWL 1 . The processing unit  16  performs conventional operations in a mobile phone and the software  15  performs operations which are required in the present technology. The transceiver BT 1  has a BLUETOOTH device address BE 1  and can be set in different modes by pressing buttons on the keyset. A first mode is e.g., for communication with a conventional BLUETOOTH headset and a second mode is for communication with the transceiver BT 2  in the stationary telephony terminal S 1 . As an alternative mode a subscriber can talk and listen via the headset, but still keys numbers on the stationary terminal. When an incoming call comes to the mobile telephone M 1  and the transceiver BT 1  is in the second mode, the call is sent on to the transceiver BT 1  by the software  15 . Among others the ring initiating signal in the call is handled by the software  15  and is transmitted to the transceiver BT 1  instead of being transmitted to the bell  21 . A telephone number keyed on the keyset  3  on the stationary terminal S 1  is transmitted via the short range link SWL 1  to the transceiver BT 1  and to the processing unit  16 . With the aid of the software  15  the telephone number is transmitted from the mobile phone via the link R 1  as if it was keyed directly on the keyset  13 . In an alternative embodiment the ring initiating signal is transmitted to both the bell  21  and to the transceiver BT 1  and in still an alternative only to the bell  21 . 
     In connection with signalling diagrams in  FIGS. 4 to 11  it will be described in closer detail how the stationary telephony terminal S 1  works and is used when communicating with the telephone S 2 . 
     Discovery Phase 1 
       FIG. 4  is a signalling diagram for the stationary telephony terminal S 1 , the mobile telephone M 1  and the base station BS 1 , in which diagram the time is denoted by T. The situation in connection with  FIG. 4  is that the stationary telephony terminal S 1  stands in a room, is powered from a common power socket and is switched on. The terminal transmits repeatedly inquiry signals  31  by its BLUETOOTH transceiver BT 2  over the BLUETOOTH short range link SWL 1 . The terminal thereby requests for contact with other BLUETOOTH devices. The subscriber P 1  comes into the room with the mobile telepone M 1  and switches it on at a moment  32 . Signals  33  are sent by the radio unit  19  on a signalling channel over the radio link R 1  between the mobile M 1  and the basestation BS 1 . The network MTN 1  recognizes the mobile M 1  and notes its geographical position. This is performed in a conventional manner and the mobile is in its standby mode. In an alternative the mobile M 1  is already switched on and has contact with the base station BS 1  when it comes in range of the BLUETOOTH transceiver BT 2  at the moment  32 . The mobile receives the inquiry signals  31  via its BLUETOOTH transceiver BT 1 . At a moment  34  the mobile M 1  sends inquiry response signals  35   a  back to the stationary terminal S 1  on the channel  35 . The response signals  35   a  includes the BLUETOOTH address and the clock time for the terminal BT 1 , according to the BLUETOOTH specifications. At a moment  36  the terminal S 1  receives the signals  35   a  and a piconet with the transceiver BT 2  as master and the transceiver BT 1  in the mobile telephone as slave is set up with a page/page response sequence as described in the BLUETOOTH specifications. This sequence is not shown in the figure. At a moment  37  the terminal BT 2  identifies itself as a stationary terminal with an identification signal. At a moment  38  the terminal BT 1  identifies itself as a mobile with an identification signal, which includes the mobile telephony number Ph 1 . The use of the stationary terminal S 1  requires in many cases an authentication as will be described in connection with  FIG. 9 . 
     In an alternative embodiment the BLUETOOTH terminal BT 2  directly pages the BLUETOOTH terminal BT 1 , if the terminal BT 2  already has the BLUETOOTH device address for the terminal BT 1 . When this terminal responds on the page the piconet is established. Also other mobile telephones with BLUETOOTH transceivers can be connected as slaves in the piconet with the transceiver BT 2  as master. If the mobiletelephone M 1  with the transceiver BT 1  moves out of range from the stationary terminal S 1  with the transceiver BT 2  so that the piconet connection is lost, when it returns the piconet will again be restored as described above. 
     Incoming Call to the Stationary Telephony Terminal S 1   
       FIG. 5  is a signalling diagram for the setting up of a call from the telephone S 2  in the public network PSTN 1  to the mobile telepone M 1 , when the mobile subscriber P 1  selects to take the call on the stationary telephony terminal S 1 . The discovery phase is already completed as described above. 
     The subscriber P 2  dials at a moment  40  the telephony number to the mobile telephone M 1  on the telephone S 2 . The call is coupled through the networks PSTN 1  and MTN 1  in conventional manner to the base station BS 1 , denoted by reference  41 . The mobile telephone is called, denoted by reference  42 , via the base station on a signalling channel over the radio link R 1  by a message “Incoming call.” At a moment  43  the mobile notes the incoming call from the telephone S 2 . By signalling  44  a speech channel between the base station BS 1  and the mobile telephone M 1  is allocated in conventional manner. The mobile M 1  is a slave in the pico network with the terminal S 1  as master. It thus transmits the message “Incoming call” on the already established BLUETOOTH channel to the terminal S 1  with the aid of the software  15 . This transmission comprises in the present embodiment the telephony number of calling telephone S 2  and is denoted by reference  45 . A ring signal is generated in the mobile M 1 , the subscriber P 1  lifts the handset  2  of the stationary terminal and the hook function  9  is activated, which is all denoted by reference  46 . A response signal is sent to the mobile, indicating that the stationary telephony terminal S 1  will answer the call (off-hook), and including an authentication code that the subscriber has keyed earlier, all denoted by reference  47 , and a speech channel over the BLUETOOTH link SWL 1  is set up. The mobile M 1  also receives the off-hook message at a moment  48 . The off hook message initiates the mobile M 1  to send a message with the aid of the software  15  to the mobile network MTN 1  via the base station BS 1 , denoted by reference  49 . This message correspond to the message which is sent when the subscriber P 1  takes a call directly on the mobile M 1  by pressing the “Answer” button. The earlier designated speech channel to the base station is set up at a moment  50  and a conversation can take place. 
     Call Released from the Stationary Telephony Terminal S 1   
       FIG. 6  is a signalling diagram for the release of the call by the stationary telephony terminal S 1 . 
     The subscriber P 1  replaces the handset  2  at a moment  52  and the hook function  9  is deactivated. As denoted by reference  53  the mobile telephone M 1  is informed of this fact via a signalling channel over the BLUETOOTH link SWL 1 . The software  15  activates the mobile telephone to signal the call release to the network over a signalling channel on the link R 1 , referenced by  54 . This is performed in the same way as if a corresponding release button on the keyset  13  of the mobile was pressed. The channel through the networks MTN 1  and PSTN is released, which is denoted by reference  55 , and the speech channel over the BLUETOOTH link SWL 1  is released, denoted by reference  56 . 
     Call Released from the Telephone S 2   
       FIG. 7  is a signalling diagram for the release of the call by the telephone S 2  in the public network PSTN 1 . 
     The subscriber P 2  goes on-hook at a moment  71 , which is signalled through the networks PSTN 1  and MTN 1  as denoted by the reference  72 . The base station BS 1  signals the call release to the mobile M 1  as denoted by the reference  73 . The processing unit with the software  15  is activated and sends a release signal to the stationary telephony terminal S 1 , denoted by reference  74 . The connection between the stationary telephony terminal S 1  and the telephone S 2  is released in a conventional manner. At a moment  75  the subscriber P 1  goes on-hook. 
     Outgoing Call from the Stationary Telephony Terminal S 1   
       FIG. 8  is a signalling diagram for the setting up of a call from the stationary telephony terminal S 1  to the telephone S 2  in the public network PSTN 1  via the mobile telepone M 1 . The discovery phase is already completed and the BLUETOOTH piconet is established as described above. 
     The subscriber P 1  lifts the handset  2  at a moment  60  and the hook function  9  is activated. The subscriber keys the telephone number to the called subscriber telephone S 2  and presses a “yes” button when the number is completed. A BLUETOOTH speech channel  61  is set up. As mentioned the subscriber P 1  has earlier keyed and stored an authentication code, which is now transmitted on the short range link SWL 1  to the mobile telephone M 1 . The authentication is accepted by the mobile M 1  as denoted by reference  62 . The button pressings in the dialled number are transmitted to the mobile telephone M 1 , which transmission is denoted by reference  63 . In an alternative the transmissions  61  and  63  are combined into one. The software  15  is activated by the transmitted button pressings and influences the processing unit  16  in the same way as if the the telephone number was keyed by the buttons on the key pad  13  of the mobile telephone M 1 . This is denoted by reference  64 . A signalling channel is set up between the mobile M 1  and the base station BS 1 , referenced  65 , and in a conventional manner a speech channel is allocated. The connection is set up through the networks MTN 1  and PSTN 1 , as denoted by reference  66 , and on a ring signal the subscriber P 2  lifts his handset on the telephone S 2 , denoted by reference  67 . This lifting is transmitted back to the base station BS 1 , denoted by reference  68 , and the earlier allocated speech channel is set up, which is denoted by reference  69 . A conversation between the subscribers P 1  and P 2  can take place. 
     In the above examples it is mentioned that the subscriber P 1  has his mobile radio telphone M 1  on, the BLUETOOTH transceivers BT 1  and BT 2  are within range of each other, the mobile M 1  has identified itself to the stationary terminal S 1 , and the subscriber P 1  has to key an authentication code on the stationary terminal S 1 , that the terminal S 1  will send to the mobile M 1 . The subscriber then can key a telephone number on the stationary telephony terminal S 1  to reach the called subscriber or take an incoming call. Authentication is desirable in many situations because the subscriber P 3  in  FIG. 1  can come into the room and bring an own mobile telephone M 3  with him, that is in standby position. When a call is keyed on the stationary terminal S 1  the question arises whose mobile telephone is to be used. Also, a person can on the sly place a stationary telephony terminal near to a mobile telephone and without permission try to make outgoing calls and take incoming calls on that mobile telephone. This is prevented by the authentication. It should anyhow be noted that in some cases the authentication is unnecessary, e.g., if the mobile phone is used in environments where only trusted persons or devices are within BLUETOOTH range, or if the functionality for connecting to stationary deskphones as described here is turned off when the mobile phone is used in non trusted environments. 
     It has been mentioned above that setting up and taking a call on the stationary terminal S 1  can involve an authentication. To facilitate the use of the stationary terminals a relation between the stationary terminal and the mobile telephone can be defined with the aid of a code as will be described below in connection with  FIGS. 9 and 11 . 
     Use of Service Code 1 
       FIG. 9  is a signalling diagram for an identification and authentication procedure between the mobile telephone M 1  and the stationary telephony terminal S 1 . As in  FIG. 4 , the stationary terminal S 1  transmits the inquiry signals  31 , announcing itself. At a moment  81  the mobile telephone M 1  is switched on and begins to interchange signals  82  with the base station BS 1  in a conventional manner. The mobile telephone M 1  is programmed, via the software  15 , to identify itself before the stationary terminal S 1  not only as a mobile telephone but as an individual one. At a moment  83  the BLUETOOTH terminal BT 1  of the mobile radio telephone M 1  receives the signal  31 , the piconet is set up as earlier described and the BLUETOOTH address BE 1  and clock time for the BLUETOOTH terminal BT 1  is transmitted according to the BLUETOOTH specification. With the aid of the software  15  the terminal BT 1  automatically transmits its telephone number Ph 1 =23397 with an identification signal  84 . At a moment  85  the stationary terminal S 1  receives, via the transceiver BT 2 , the signal  84 . It now has safely the information that the BLUETOOTH trasceiver BT 1 , with the identity BE 1 , represents the individual mobile radio telephone M 1  with the telephone number Ph 1 =23397. This information is stored. Note that stationary terminal S 1  not yet can be used for a call via the mobile telephone M 1 . Other mobile telephones, e.g., the mobile telephone M 3 , can move near to the stationary telephony terminal S 1  and identify themselves in the same manner. 
     The subscriber P 1 , owner of the mobile M 1 , now has to key a code on the stationary telephony terminal S 1  to set this terminal in a mode for communicating with the mobile telephone M 1 . 
     First a service code  91 ,  92  or  93  is to be keyed, indicating how long a time interval for the communication mode will be. Then the telephone number 23397 of the mobile radio telephone M 1  has to be keyed and at last, for authentication, the PIN-code 1234 of the mobile phone M 1  is keyed. Thus the total code *9 — 23397*1234# is keyed at a moment  86 , where  9 _ denotes any of the service codes. The keyed information is stored in the stationary telephony terminal S 1 . A relation between the mobile telephone M 1  and the stationary telephony terminal is now established. Provided that the entered PIN code is correct, outgoing calls can now be set up and incoming calls can be taken on the stationary telephony terminal S 1 . From the telephone number 93397, the stationary telephony terminal S 1  knows the corresponding BLUETOOTH address BE 1  of the mobile telephone M 1  to which messages should be sent, and by providing the PIN code, the stationary telephony terminal S 1  shows to the mobile telephone M 1  that it is authorised to communicate via the mobile telephone M 1 . 
     The PIN code is not sent from the stationary telephony terminal S 1  to the mobile telephone M 1  until a call is actually to be made or answered on the stationary telephony terminal S 1 . 
     In an alternative, when the PIN code 1234 has been entered it is transmitted in a message  87  to the mobile telephone M 1 . The mobile telephone M 1  receives the message at a moment  88  and checks the PIN code for correctness in the time interval  89 . At a moment  90  the mobile telephone M 1  sends a reply message  95  to the stationary telephony terminal S 1 , indicating if the PIN code was correct or not. The stationary telephony terminal S 1  receives the message and can indicate the result to the user by an audiable message or a message on the display. 
     When the stationary telephony terminal S 1  receives an “incoming call” message from another mobile telephone, e.g., the mobile telephone M 3 , it will find out by checking the previously stored information, that the telephone number Ph 3  that corresponds to the BLUETOOTH device address of M 3 , is not the number Ph 1  of the mobile telephone M 1 , with which the stationary telephony terminal S 1  currently has a relation. Therefore, the terminal S 1  will not sound a ring signal. 
     As mentioned in the example above the service code  91 ,  92  or  93  has to be keyed. In the example the service code is denoted by  9 _ to cover all situations. The service code is given the following meaning in the present example: 
     Code  93  is permanent and is intended to be used by, e.g., the subscriber P 1  having the stationary telephony terminal on his ordinary desk. Once the subscriber has keyed the code *9323397*1234#, he needs not to key it again. He needs only to have his mobile telephone M 1  on, key a telephone number to a called subscriber on the stationary terminal S 1  or directly take an incoming call on the stationary terminal S 1 . This situation will endure for as long time as the subscriber decides. 
     Code  92  is to be used in the same way as code  93 , with the exception that it will only endure for a limited time interval. This interval can be e.g., one day or for as long time as the mobile telephone is in range of the short range transceiver BT 2 . 
     Code  91  is intended to be used for one call only. The subscriber P 3  with the mobile telephone M 3  in standby position comes into the room in which the stationary telephony terminal S 1  is located, see  FIG. 1 . The mobile telephone M 3  has a number 23399. When the subscriber P 3  wants to make a call on the stationary terminal S 1 , he first has to key his code *9123399*4321# on the stationary telephony terminal S 1  and can then make the call. When the call is finished the code will be deleted. If a call comes to the mobile telephone M 3  and the subscriber P 3  wants to take the call on the stationary telephony terminal S 1 , the subscriber has to first key his code *9123399*4321#. 
     The processor  6  in the stationary terminal S 1  can be programmed such that a lower-number service code overrides a higher number, but when the session or the call with the overriding service code ends, the previous service code is restored. This means that a subscriber, having the stationary terminal in his office, can key the service code  93  and always have access to the terminal when in office. Still someone else can use the stationary terminal for a call by keying the service code  91 . The stationary terminal can also be conveniently used by a person visiting the office for a few hours by keying the service code  92 . When this person leaves the office the stationary telephony terminal goes back to the original subscriber. Many persons can be in a room with a stationary telephony terminal and have their mobile radio telephones in standby mode. When a mobile telephone rings the person can immediately take the call on the stationary terminal by using the service code  91 . 
     In the above embodiment it is the telephone number Ph 1  of the mobile radio telephone M 1  that is the identification code. As an alternative to the telephone number Ph 1  the subscriber can select another own code. 
     The authentication number is, in the above embodiment, the PIN code of the mobile telephone M 1 . Also other authentication codes can be used that the subscriber selects. 
     The subscriber had to key the service code  9 _ in the above embodiment, before the called subscriber&#39;s telephone number was keyed. The service code, if any, can be performed in a number of different ways. It can e.g., comprise only two codes, one for permanent authentication and one for a single call. It can also have codes on top of the codes  91 ,  92  and  93 , e.g., a code for a predetermined number of calls decided by the owner of stationary telephony terminal S 1 . 
     Also, in the above embodiment, the authentication was checked in the mobile telephone M 1  during the time interval  89 . Such a check can be transmitted from the mobile telephone M 1  over the link R 1  to the base station BS 1 . The authentication check is then performed in the land system of the mobile radio telephony network MTN 1 . 
     In the above embodiment the service code was given by pressing buttons  91 ,  92  or  93  on the keypad of the stationary terminal S 1 . An alternative is that the terminal has a button designated for each of the codes or a corresponding menu driven interface. 
     In the above embodiments the stationary terminal S 1  sends the inquiry signal from the BLUETOOTH transceiver to establish the pico network according to the BLUETOOTH specification. If the BLUETOOTH transceiver of the mobile telephone is known to the BLUETOOTH transceiver of the stationary terminal, it can make a page which is somewhat faster than an inquiry. 
     Discovery Phase 2 
       FIG. 10  is a signalling diagram for the stationary telephony terminal S 1 , the mobile telephone M 1  and the base station BS 1 . The situation in connection with  FIG. 10  is that the stationary telephony terminal S 1  stands in a room, is powered from a common power socket and is switched on. Compared with the situation in  FIG. 4 , Discovery phase 1, in  FIG. 10  it is the mobile radio telephone M 1  that sends inquiry signals. The subscriber P 1  comes into the room with the mobile telepone M 1  and switches it on at a moment  101 . Signals  102  are sent by the radio unit  19  on a signalling channel over the radio link R 1  between the mobile telephone M 1  and the basestation BS 1 . The network MTN 1  recognizes the mobile telephone M 1  and notes its geographical position. This is made in a conventional manner and the mobile telephone is in its standby mode. At a moment  103  the mobile telephone begins to repeatedly send inquiry signals  104  by its BLUETOOTH transceiver BT 1  on a channel  105  over the BLUETOOTH short range link SWL 1 . The stationary telephony terminal S 1  receives the inquiry signals  104  via its BLUETOOTH transceiver BT 2  and at a moment  106  it sends inquiry response signal  107  back to the mobile telephone M 1 . The response signal  107  includes the address and the clock time for the BLUETOOTH terminal BT 2 . At a moment  108  the mobile radio telephone M 1  receives the signal  107 . A piconet with M 1  as master is then established through a page/page response sequence as described in the BLUETOOTH specification (not shown). In an alternative, a master/slave switch is then performed so that the stationary telephony terminal S 1  becomes the master of the piconet. 
     Use of Service Code 2 
       FIG. 11  is a signalling diagram for an identification and authentication procedure between the mobile telephone M 1  and the stationary telephony terminal S 1 . In this embodiment it is the mobile telephone M 1  that transmits the inquiry signal. At a moment  111  the mobile telephone M 1  is switched on and begins to interchange the signals  102  with the base station BS 1  in a conventional manner. The mobile telephone M 1  is programmed, via the software  15 , to identify itself before the stationary terminal S 1  not only as any mobile telephone but as an individual one. At a moment  112  the mobile radio telephone M 1  transmits the inquiry signal  113 . At a moment  115  the stationary terminal S 1  receives, via the transceiver BT 2 , the inquiry signal. At a moment  116  the stationary telephony terminal S 1  sends an inquiry response signal  117  back to the mobile radio telephone M 1 . A piconet with the mobile M 1  as master is then established through a page/page response sequence as described in the BLUETOOTH specification (not shown). In an alternative, a master/slave switch is then performed so that the stationary telephony terminal S 1  becomes the master of the piconet. With the aid of the software  15  the mobile telephone also automatically transmits its telephone number Ph 1 =23397 from the BLUETOOTH transceiver BT 1  with an identification signal  118 . The terminal S 1  identifies itself as a stationary telephony terminal with an identification signal  119 . The terminal S 1  now safely has the information that the BLUETOOTH transceiver BT 1 , with the identity BE 1 , represents the individual mobile radio telephone M 1  with the telephone number Ph 1 =23397. This information is stored. Other mobile telephones, e.g., the mobile telephone M 3 , can move near to the stationary telephony terminal S 1  and identify themselves in the same manner. The subscriber P 1 , owner of the mobile M 1 , now has to key the previous mentioned code on the stationary telephony terminal S 1  to set this terminal and the mobile telephone M 1  in a mode for communicating with each other. This communication is performed as described in connection with  FIG. 9  and is not shown in  FIG. 11 . 
     In connection with flow charts in  FIGS. 12 to 15  the above described methods in connection with the stationary telephony terminal S 1  will be described in summary. 
       FIG. 12  shows a flow chart with the above “Discovery phase 1”. In a step  121  the stationary telephony terminal S 1  is powered on. Step  122  shows the transmitting of the inqury signals  31  from the stationary terminal S 1 . The mobile radio telephone M 1  is powered on in a step  123 , and in a step  124 , the mobile telephone is connected to the mobile radio telephony network MTN 1 . In a step  125 , the mobile telephone M 1  receives the inquiry signal and sends the inquiry response signal  35   a  in a step  126 . A piconet is established in a step  127 . In a next step  128 , the terminal S 1  identifies itself as a stationary telephony terminal, and in a step  129 , the mobile M 1  identifies itself as a mobile radio telephone. 
       FIG. 13  shows a flow chart with the above “Discovery phase 2”. In a step  131  the stationary telephony terminal S 1  is powered on and in a step  132  the mobile radio telephone M 1  is powered on. The mobile M 1  is connected to the mobile radio telephony network MTN 1  in a step  133  and in a step  134  the mobile transmits the inquiry signal  104 . The stationary terminal S 1  receives the inquiry signal  104  in a step  135  and in a step  136  it transmits the inquiry response signals  107  to the mobile telephone M 1 . A piconet is established in a step  137 . In a step  138  the mobile M 1  identifies itself as a mobile radio telephone with its number and in a step  139  the stationary terminal S 1  identifies itself as a stationary telephony terminal. 
       FIG. 14  shows a flow chart over a procedure use of service code when a call is made. It is presumed that the stationary telephony terminal S 1  is powered on and the mobile radio telephone M 1  is also powered on and is in contact with the mobile radio telephony network MTN 1  via the radio link R 1 . In a step  140  the stationary terminal S 1  transmits the inquiry signal  31  and in a step  141  the mobile radio telephone M 1  receives these inquiry signals. Trigged by the inquiry signal the mobile telephone M 1  transmits the inquiry response signal  84  with the BLUETOOTH identity BE 1  in a step  142 . In a step  143  the piconet is set up and in a step  144  the telephone number Ph 1 =23397 is transmitted to the stationary terminal S 1 . To be able to use the stationary terminal for a call the subscriber P 1  now keyes on the stationary terminal S 1  the service code  9 _ in a step  145 . In a step  146  the subscriber keyes the mobil&#39;s phone number Ph 1 =23397 on the stationary terminal and in a step  147  the subscriber keyes the mobile&#39;s PIN code 1234 on the stationary terminal S 1 . The stationary terminal is now ready for use for as long time as the service code  9 _ permits. The subscriber P 1  keyes the number to the called subsriber S 2  and presses the “yes” button in a step  148 . In a step  149  the keyed subscriber number and the total code *9 — 93397*1234# is transmitted from the stationary terminal S 1  to the mobile telephone M 1  in a step  149 . In a step  150  it is checked that the PIN code is correct. This check can be performed in the mobile telephone M 1  or in the land system of the mobile network MTN 1 . If the code is wrong, an alternative “NO”, the call is rejected in a step  151 . If on the other hand the code is correct, an alternative “YES”, a BLUETOOTH speech channel is set up on the link SWL 1 , step  152 . In a step  153  the mobile M 1  initiates a call to the telephone S 2 . 
     The above described non-limiting and example embodiments can be further varied in a number of ways. An example is that the BLUETOOTH transceivers BT 1  and BT 2  can be replaced by optical IR transceivers. Another example is that the keying of telephone numbers on the keypad  3  can be replaced by voice commands, which are processed in the device  3   a.