Abstract:
Methods and apparatus support communication between a communication device and a compatible communication device over a telecommunications network. The communication devices have unique identities. The methods and apparatus are configured to detect the presence of the compatible communication device using a low power radio frequency technology; to determine the identity of the detected compatible communication device; and, in response to detection of the presence of the compatible communication device, to redirect incoming calls intended for the detected compatible communication device having the determined identity to the communication device, wherein the controller sends control signals to the compatible communication device, such that the compatible communication device can control the redirection of the incoming calls at the network.

Description:
TECHNICAL FIELD 
   The present invention relates to radiotelephones and, more particularly, to the management of multiple radiotelephones. 
   BACKGROUND 
   In recent years, the penetration of handheld portable radiotelephones has grown enormously, and now, in many countries, the majority of people possess a portable radiotelephone. Of these people, an increasing number also posses more than one portable radiotelephone, for example a car phone and a handheld mobile radiotelephone. One problem with this is that a user ends up having multiple telephone numbers and people trying to contact the user do not know on which radiotelephone the user is may be contacted. 
   Accordingly, one aim of the present invention is to overcome the above-mentioned problems of the prior art. 
   SUMMARY OF THE INVENTION 
   According to a first aspect of the present invention, there is provided a communication device for communicating with a compatible communication device over a telecommunications network, wherein the communication devices have unique identities, the communication device comprising: a detector for detecting the presence of the compatible communication device; determination means for determining the identity of the detected compatible communication device; and a controller effective for redirecting incoming calls intended for the detected compatible communication device having the determined identity to the communication device. 
   According to a second aspect of the present invention, there is provided a method of redirecting calls to a communication device from a compatible communication device, wherein the communication device and the compatible communication device have unique identities and are capable of communicating over a telecommunications network, the method at the communication device comprising: detecting the presence of the compatible communication device; determining the identity of the detected compatible communication device; and redirecting incoming calls intended for the compatible communication device having the determined identity to the communication device. 
   According to a third aspect of the present invention, there is provided a communications system having a first and a second communication device each having a unique identity and capable of being connected via a telecommunications network, wherein the first communication device comprises: a detector for detecting the presence of the second communication device; means for determining the identity of the second communication device; a controller effective for redirecting calls intended for the second communication device having the determined identity to the first communication device. 
   One advantage of the present invention is that a user is always contactable on whichever telephone they are currently using. This prevents people trying to contact the user from having to try multiple numbers in order to reach the user. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
       FIG. 1  shows a first embodiment of the present invention according to the present invention; 
       FIG. 2  is a block diagram showing the telephone  100  of  FIG. 1  in greater detail; and 
       FIG. 3  is a flow diagram outlining the main steps of one embodiment according to the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a mobile phone  100 , preferably mounted in a fixed location such as a car. The mobile phone, hereinafter referred to as car phone  100 , has a detector (not shown) which can detect the presence of a compatible mobile telephone  101  within a range  102 . 
   For the purposes of this description the term car phone will be used to describe a mobile telephone mounted in a car, and the term mobile telephone will be used to describe a hand-held mobile telephone. 
   If the user has both a car phone and a mobile telephone this can cause severe confusion for people trying to contact the user. For example, whilst driving the car the user may be unable, due to safety reasons or legislation, to use his mobile telephone. Additionally, whilst out of the car the user will not be able to answer the car phone. Someone trying to contact the user on his mobile telephone number whilst he is driving will therefore be unable to be connected, unless he redials using the number of the car phone. Someone trying to call the user will therefore will require both the number of the car phone and the mobile telephone and may have to try calling both numbers in order to reach the user, depending on whether the user is in or out of the car. 
   Each of the telephones  100  and  101  contain a subscriber identification module (SIM) which provide each of the telephones with a unique subscriber number (i.e. a telephone number). In this way, each of the telephones  100  and  101  may operate independently. However, as described above, this does present the user with a number of problems. 
   When the mobile telephone  101  is detected within the range  102  of the car phone  100 , the car phone  100  can be programmed to perform a number of predetermined tasks. Such tasks may include initiating network based call forwarding from the mobile telephone to the car phone, determining the identity of the detected phone, authorising the detecting phone etc . . . 
   For example, when a user having a mobile telephone enters a car having a car phone, the car phone detects the presence of the mobile telephone and causes all subsequent phone calls to the mobile telephone to be diverted to the car phone. In this way, calls to the mobile telephone may be safely answered using the car phone. Typically a car phone is specially designed to be safely operated whilst driving and may include features such a separate loudspeaker and microphone, a separate display and a separate control panel. When the user leaves the car, the car phone no longer detects the presence of the mobile telephone and cancels the call forwarding. This arrangement enables the user to be always contactable on a single subscriber number, that of his mobile telephone. 
   In an embodiment having a car phone, it is preferable that the range in which a compatible telephone can be detected is limited so as not to extend beyond the perimeter of the car. This is to prevent unintentional detection of compatible telephones whilst outside of the car. 
     FIG. 2  is a block diagram showing the telephone  100  of  FIG. 1  in greater detail. 
   The mobile telephone  100  of  FIG. 1  has a central processor  202  which is connected to a control module  204  which controls the expected functions of a mobile telephone, such as the key pad, call management, display, etc. These functions will not be described in detail as they are well understood in the art, and do not directly form part of the present invention. An antenna  206  is used to transmit signals to and to receive signals from a cellular or other wireless telecommunications network. Also connected to the processor  202  is a module  208  which controls the function of a local wireless connection, via an antenna  210 . The module  208  may use low power radio frequency (LPRF) technology, such as the commonly called Bluetooth standard, to communicate to similarly equipped devices. Alternatively, the module  208  may use any other appropriate communication medium, for example, an infra-red link, or even a direct electrical connection which may be provided through a mobile phone holder. 
   In LPRF communications it is common for one device to act as a master to other slave devices. In the present embodiment it is preferred that the car phone acts as the master device, and the mobile phone acts as the slave device, although the invention will work equally well with the reverse arrangement. The car phone transmits a signal over the LPRF network requesting other compatible devices to respond over the LPRF network. Since the car phone transmits these requests frequently this increases the power requirements of the car phone. It is for this reason that it is preferable that the car phone is chosen to be the master device, since the car phone will generally be connected to a large capacity car battery. 
   When a compatible device, such as the mobile phone  101  is within range of the master LPRF signal transmitted by the car phone, the request signal is received by the slave LPRF module of the mobile phone  101 . The slave LPRF module of mobile phone  101  transmits a signal to the master LPRF module of the car phone  100  indicating that the mobile phone  101  is within range of the car phone  100 . The precise details regarding handshaking between the master and slave devices will not be discussed in detail here since they will be apparent to those skilled in the art. However, an outline of the steps undertaken by a master LPRF device according to one embodiment of the present invention are shown in  FIG. 3 . 
   The master LPRF module of the car phone  100  attempts to detect, at a step  300 , the presence of a compatible mobile telephone  101  within transmission range of its signal. If no compatible mobile telephone is detected, the master LPRF module of the car phone  100  periodically transmits a request that any compatible device acknowledges with an appropriate response signal. Once a compatible device has been detected an authorisation step  302  is performed. The authorisation step  302  ensures that only authorised mobile telephones be used with the car phone. The authorisation step  302  determines the identity of the detected device, for example by determining the subscriber number of the device. Authorisation consists of comparing the identity of the detected device with a list of previously authorised identities. If the identity of the detected device is among the list of previously authorised identities, authorisation may be given, otherwise authorisation may be refused. Additionally, authorisation may require, for example, the entering of a security code by the user, either on the mobile phone or on the car phone in order to complete the authorisation step. 
   The car phone may also be configured to allow any compatible device to be used, regardless of identity. 
   The car phone  100  may, optionally at step  304 , request confirmation from the user of the mobile telephone to initiate call forwarding from the mobile telephone  101  to the car phone  100 . If the mobile phone user does not accept call forwarding, the master LPRF device of the car phone  100  returns to execute step  300 . 
   The authorisation step may also add to the list of authorised mobile telephones any mobile telephones which are successfully used with the car phone. In other words, once a mobile telephone has been authorised for use with the car phone once, it will always be authorised until it is removed from the authorisation list. 
   If the user accepts activation of call forwarding, the car phone  100  initiates call forwarding of the mobile phone  101  to the car phone  100  at a step  306 . In an alternative embodiment the car phone  100  may instruct the mobile telephone  101  to initiate call forwarding from the mobile telephone  101  to the car phone  100 . The call forwarding may be performed on the network, by sending appropriate control signals to the network such that calls made to a given subscriber number are automatically re-routes to a forwarded number. Alternatively, call forwarding may be established by a mobile telephone handset itself. In this case, when a call arrives at a mobile telephone, the mobile telephone makes a new call to the forwarded number, and connects the calls together. 
   Once call forwarding is initiated, the master LPRF device of the car phone  100  periodically checks to see whether the mobile telephone  101  is still within range of the car phone. As soon as the mobile telephone  101  is no longer within range, for example when the user leaves the car with his mobile phone, call forwarding is automatically cancelled by the car phone  100 . In an alternative embodiment the mobile telephone  101  acts to cancels the call forwarding when out of range of car phone  100 . Preferably call forwarding is also cancelled whenever the LPRF link is broken, for example when the mobile telephone is switched off or when the battery of the mobile telephone runs out. It may be preferable in these instances to request confirmation from the user, via the car phone  100 , as to whether call forwarding should be cancelled. If no response is received from the user within a given time period call forwarding may be cancelled automatically. 
   In yet a further embodiment of the present invention, the call forwarding performed by either the car phone  100  or the mobile phone  101  is user customisable. For example, there are many telephone companies which now provide so called personal or non-geographic telephone numbers. This allows a user to choose an easy to remember telephone number. Such telephone numbers are not associated with any particular telephone, but are forwarded to a predetermined telephone number. The call forwarding capability of the car phone or the mobile phone enables call forwarding of the personal number to which ever device is currently in use. For example, when a user enters the car, the car phone causes the personal number to be forwarded to the car phone. When the user leaves the car, the car phone causes the personal number to be forwarded to the mobile telephone. 
   In yet a further embodiment of the present invention, the mobile phone acts as the master LPRF device, and the car phone acts as the slave LPRF device. 
   It is common when using call forwarding that the telephone which is being forwarded is charged for the forwarded portion of the call. The telecommunications network operator, however, can arrange for these charges not to be incurred. The network operator can also arrange that calls made by the car phone, whilst having calls forwarded to it from a mobile telephone, show the caller line identification (CLI) of the forwarded mobile telephone. Additionally, the network operator can also arrange that calls made in this manner are billed to the forwarded telephone. In this way, calls made from the car phone will appear to be made by the mobile telephone which is forwarded thereto. 
   Although the present invention is described above with reference to a car phone and a mobile telephone, it will be appreciated that the car phone could be replaced by any other fixed or semi-permanent telephone having an LPRF module. For example, the present invention could also be used in an office or home environment. Additional embodiments provide that, for example in an office environment, when a user is at his desk, calls to a mobile telephone are forwarded to a desktop phone connected to a private switched telecommunications network (PSTN). When the user is away from his desk, this is automatically detected by the desktop phone (or the mobile telephone) and calls to the desktop phone may be automatically forwarded to the mobile telephone. 
   Those skilled in the art will appreciate that other combinations are also possible within the scope of the present invention. For example, the presence of the car phone could be detected by a mobile telephone, and the mobile telephone could effect the call forwarding in response to the detection. 
   Reference above to mobile telephone or car phone is also intended to include reference to radiotelephones and portable radiotelephones.