Abstract:
A communications terminal device and a method performed by a communications terminal device wherein packet data received from a Wireless Personal Area Network (WPAN) headset (such as, for example, a Bluetooth headset), which comprises an encoded audio signal, is directly convened by the terminal device to Internet Protocol (IP) packets which are transmitted across a Voice over Internet Protocol (VoIP) communications network, wherein speech encoding is not performed by the terminal device. Similarly, a communications terminal device and a method performed by a communications terminal device wherein IP packet data comprising an encoded audio signal is received from a VoIP communications network by the terminal device, and is directly converted by the terminal device to WPAN packets (such as, for example, Bluetooth protocol packets) which are transmitted to a WPAN headset (such as, for example, a Bluetooth headset), wherein speech decoding is not performed by the terminal device.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to the field of Voice over Internet Protocol (VoIP) speech communications networks, and more particularly to a method and apparatus for performing high quality speech communication across such networks. 
       BACKGROUND OF THE INVENTION 
       [0002]    Voice (i.e., speech) quality over the telephone has been relatively static for decades, since conventional circuit-switched telephone networks have a fundamental bandwidth limitation of 3400 Hz (Hertz). As such, conventional Public Switched Telephone Network (PSTN) and mobile phone network communications are currently limited to the frequency range of 300 Hz to 3400 Hz. However, the recent migration of voice communication into VoIP (Voice over Internet Protocol) communications networks opened a new era of possibilities to voice quality improvement. In particular, packet-based speech delivery over Internet Protocol (IP) networks can boost voice quality by extending the audio frequency range of transmitted speech signals beyond the conventional audio bandwidth limitation of 3400 Hz (as imposed by circuit-switched networks). In mobile voice communications, for example, High Definition (HD) voice is about to be introduced. Specifically, HD (i.e., “wideband”) voice provides much better quality and clarity than does conventional (i.e., “narrowband”) voice by covering the frequency range of 50 Hz to 7000 Hz. In general, such HD voice will be enabled by wideband speech coders in handsets that encode the acoustic signal captured through the handset microphone with a higher quality speech coder than do conventional narrowband speech coders. 
         [0003]    However, Wireless Personal Area Network (WPAN) wireless headsets, such as Bluetooth (BT) headsets, are now being widely used, particularly among mobile phone users, for hands-free communication. Specifically, when a BT headset is used, an acoustic speech signal is captured through the microphone in the headset; the resultant audio signal waveform is compressed by an audio encoder; and the encoded audio signal is then transmitted to the mobile handset using the well-defined BT protocol. In the handset, the received encoded audio signal (i.e., the BT signal) is then decompressed by an audio decoder (which corresponds to the audio encoder in the BT headset) to produce a waveform, and the resultant waveform is then compressed again by a speech encoder for transmission through the network. Similar processing is performed in the reverse direction from the network back to a loudspeaker in the BT headset, except that there is typically a jitter buffer placed in front of the speech decoder in the handset to absorb the impact of network jitter (i.e., varying transmission delays of packets through the network). But audio codecs (i.e., encoder/decoder pairs) generally cover the audio spectrum up to 20 kHz (kilo Hertz) at very high bit rates above 100 kbps (kilobits/second), whereas speech codecs typically cover only up to either 3.4 kHz (for conventional “narrowband” speech codecs, such as, for example, Enhanced Variable Rate Codecs [EVRC] and Adaptive Multi-Rate [AMR] codecs), or 7 kHz (for more recently available “wideband” [WB or HD] codecs, such as, for example, AMR-WB), and typically operate at very low bit rates of approximately 10 kbps. 
         [0004]    For the above reasons, there are several limitations encountered when using conventional (fixed or mobile) handsets with BT headsets. First, the audio bandwidth in current network environments is restricted by the limitations of the speech codec, despite the fact that a much higher quality audio codec is employed by the BT headset and that VoIP networks are capable of handling higher quality audio. For example, general audio signals (such as background sound or music) are handled quite poorly by speech codecs, since speech codecs are specifically designed for speech signals. And second, there is excessive latency (i.e., delay) in the processing path due to the fact that two coding processes—an audio codec and a speech codec—must be performed, with the more significant contribution to the total latency coming from the speech codec. 
       SUMMARY OF THE INVENTION 
       [0005]    The instant inventors have recognized that higher quality and lower latency speech communication may be advantageously provided over a VoIP communications network when Wireless. Personal. Area Network (WPAN) headsets (such as, for example, BT headsets) are being used. In particular, by taking advantage of the fact that such WPAN headsets typically include high quality audio codecs, the inventors have recognized that the speech encoding and decoding conventionally performed by mobile or wired handsets may be advantageously bypassed. As a result, higher quality and lower latency speech communication may be advantageously performed across VoIP communications networks. 
         [0006]    Specifically, in accordance with certain illustrative embodiments of the present invention, encoded audio signal packets which have been transmitted to a terminal device (e.g. a handset) by a BT headset (using the BT protocol) may advantageously be directly converted into Internet Protocol (IP) packets—such as, for example, Real-time Transport Protocol (RTP) packets—by the terminal device, and then, these IP (e.g., RTP) packets, may be advantageously transmitted directly (i.e., without performing speech encoding) by the terminal device across the VoIP communications network. Similarly, in accordance with certain illustrative embodiments of the present invention, such IP (e.g., RTP) packets received at another (i.e., a recipient) terminal device (e.g., a handset) may be advantageously and correspondingly converted directly (i.e., without performing speech decoding) back to BT protocol packets for transmission by the recipient terminal device to another BT headset. 
         [0007]    More specifically, in accordance with various illustrative embodiments of the present invention, a terminal device and a method performed by a terminal device are provided wherein packet data received from a BT headset which comprises an encoded audio signal is directly converted by the terminal device to RTP packets which are transmitted across the VoIP communications network, and wherein speech encoding is not performed by the terminal device. Similarly, in accordance with various illustrative embodiments of the present invention, a terminal device and a method performed by a terminal device are provided wherein RTP packet data comprising an encoded audio signal is received from a VoIP communications network by the terminal device and is directly converted by the terminal device to BT protocol packets which are transmitted to a BT headset, and wherein speech decoding is not performed by the terminal device. 
         [0008]    In accordance with one illustrative embodiment of the present invention, a method performed by a terminal device for communicating speech across a Voice over Internet Protocol (VoIP) communications network is provided, the method comprising receiving a sequence of encoded audio signal packets using a wireless receiver, the encoded audio signal packets comprising data representative of speech, the encoded audio signal packets received from a Wireless Personal Area Network (WPAN); directly converting the received sequence of encoded audio signal packets into a corresponding sequence of Internet Protocol (IP) packets, wherein said conversion from said sequence of encoded audio signal packets to said sequence of IP packets is performed without the use of a speech encoder; and transmitting the sequence of IP packets across the VoIP communications network 
         [0009]    In accordance with another illustrative embodiment of the present invention, a method performed by a terminal device for receiving speech which has been transmitted across a Voice over Internet Protocol (VoIP) communications network is provided, the method comprising receiving a sequence of Internet Protocol (IP) packets from the VoIP communications network, the IP packets comprising data representative of speech; directly converting the received sequence of IP packets into a corresponding sequence of encoded audio signal packets, wherein said conversion from said sequence of IP packets to said sequence of encoded audio signal packets is performed without the use of a speech decoder, and transmitting the sequence of encoded audio signal packets across a Wireless Personal Area Network (WPAN) using a wireless transmitter. 
         [0010]    And in accordance with yet another illustrative embodiment of the present invention, a terminal device for communicating speech across a Voice over Internet Protocol (VoIP) communications network is provided, the device comprising a wireless receiver which receives a sequence of encoded audio signal packets, the encoded audio signal packets comprising data representative of speech, the encoded audio signal packets received from a Wireless Personal Area Network (WPAN); a packet conversion module which directly converts the received sequence of encoded audio signal packets into a corresponding sequence of Internet Protocol (IP) packets, wherein said conversion from said sequence of encoded audio signal packets to said sequence of IP packets is performed without the use of a speech encoder; and a packet transmitter which transmits the sequence of IP packets across the VoIP communications network. 
         [0011]    And in accordance with still another illustrative embodiment of the present invention, a terminal device for receiving speech which has been transmitted across a Voice over Internet Protocol (VoIP) communications network is provided, the terminal device comprising a packet receiver which receives a sequence of Internet Protocol (IP) packets from the VoIP communications network, the IP packets comprising data representative of speech; a packet conversion module which directly converts the received sequence of IP packets into a corresponding sequence of encoded audio signal packets, wherein said conversion from said sequence of IP packets to said sequence of encoded audio signal packets is performed without the use of a speech decoder; and a wireless transmitter which transmits the sequence of encoded audio signal packets across a Wireless Personal Area Network (WPAN). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  shows a VoIP communications network environment in which various illustrative embodiments of the present invention may be advantageously implemented. 
           [0013]      FIG. 2  shows a block diagram of a prior art user environment for use in communicating across a VoIP communications network, the user environment comprising a Bluetooth headset and a handset adapted for use therewith. 
           [0014]      FIG. 3  shows a block diagram of an illustrative user environment for use in communicating across a VoIP communications network, the illustrative user environment comprising a Bluetooth headset and a handset adapted for use therewith, the illustrative user environment providing for high quality speech communication in accordance with an illustrative embodiment of the present invention. 
           [0015]      FIG. 4  shows a flowchart of a method for converting a sequence of Bluetooth Protocol packets to a corresponding sequence of Real-time Transport Protocol (RTP) packets in accordance with an illustrative embodiment of the present invention, along with a sample of the operation of the illustrative method shown therein. 
           [0016]      FIG. 5  shows a flowchart of a method for convening a sequence of Real-time Transport Protocol (RTP) packets to a corresponding sequence of Bluetooth Protocol packets in accordance with an illustrative embodiment of the present invention, along with a sample of the operation of the illustrative method shown therein. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]      FIG. 1  shows a VoIP communications network environment in which various illustrative embodiments of the present invention may be advantageously implemented. As shown in the figure, user  11  is wearing Bluetooth headset  12  for performing Wireless Personal Area Network (WPAN) communication with handset  13 . Similarly, user  14  is wearing Bluetooth headset  15  for performing Wireless Personal Area Network (WPAN) communication with handset  16 . Handset  13  and handset  16 , each of which may, for example, be either a wired handset or a mobile handset, are communicating with each other across VoIP network  17 , enabling a conversation between user  11  (using Bluetooth headset  12 ) and user  14  (using Bluetooth headset  15 ). In accordance with various illustrative embodiments of the present invention, handset  13  and handset  16  may be advantageously implemented in accordance with the principles shown in  FIG. 3 . (See below.) 
         [0018]      FIG. 2  shows a block diagram of a prior art user environment for use in communicating across a VoIP communications network, the user environment comprising a Bluetooth headset and a handset adapted for use therewith. The user environment includes Bluetooth (BT) headset  21 , wirelessly connected (shown as direct arrowed connections for ease of understanding signal flow) to handset  22 , which is in turn connected to VoIP network  24 . In particular, to support the use of BT headset  21 , handset  22  includes therein Bluetooth (BT) chipset  23 . Note that handset  22  may be either a mobile handset (in which case VoIP network  24  comprises, at least in part, a wireless IP network, and wherein handset  22  is wirelessly connected thereto) or a wired handset (in which case VoIP network  24  comprises, at least in part, a wired IP network, and wherein handset  22  is connected thereto via a wired connection). 
         [0019]    BT headset  21  comprises microphone  211 , audio encoder  212 , BT transmitter  213 , BT receiver  214 , audio decoder  215 , and loudspeaker  216 . Handset  22  comprises, in addition to BT chipset  23 , speech encoder  221 , VoIP packetization module  222 , RTP transmitter and receiver  223 , jitter buffer  224 , and speech decoder  225 . BT chipset  23  in turn comprises BT receiver  231 , audio decoder  232 , audio encoder  233 , and BT transmitter  234 . 
         [0020]    In operation in the “forward” direction when BT headset  21  is being used (i.e., for transmitting speech across the VoIP network when the BT headset user is speaking), instead of capturing audio (e.g., speech) directly with use of handset  22 &#39;s own microphone (not shown in the figure), an acoustic signal is captured through microphone  211  in the BT headset, producing an audio waveform. The audio waveform is then compressed by audio encoder  212  and wirelessly transmitted by BT transmitter  213  to handset  22  using a BT protocol. In handset  22 , BT receiver  231  wirelessly receives this BT signal (which comprises encoded audio signal packets) and then audio decoder  232  decompresses the signal back into an audio waveform. Then, speech encoder  221  compresses this audio waveform (again), and VoIP packetization module  222  converts the encoded speech signal into IP packets—typically in Real-time Transport Protocol (RTP) form—to be transmitted by RTP transmitter and receiver  223  across VoIP network  24 . 
         [0021]    Similarly, in operation in the “reverse” direction (i.e., for receiving speech from the VoIP network when the BT headset user is listening), RTP transmitter and receiver  223  receives IP packets—typically in Real-time Transport Protocol (RTP) form—which it stores in jitter buffer  224 . (As is well known to those of ordinary skill in the art, a jitter buffer is used to absorb the impact of network jitter—i.e., varying transmission delays of packets through the network.) Then, the stored packet data is read out of jitter buffer  224  and decompressed by speech decoder  225 , producing an audio waveform. When BT headset  21  is being used, rather than handset  22  playing the audio waveform through its own loudspeaker (not shown in the figure), audio encoder  233  (re-)compresses the audio waveform and BT transmitter  234  wirelessly transmits this signal to BT headset  21  using a BT protocol. In BT headset  21 , BT receiver  214  wirelessly receives this BT signal and audio decoder  215  decompresses the signal back into an audio waveform for playout by loudspeaker  216 . 
         [0022]      FIG. 3  shows a block diagram of an illustrative user environment for use in communicating across a VoIP communications network, the illustrative user environment comprising a Bluetooth headset and a handset adapted for use therewith, the illustrative user environment providing for high quality speech communication in accordance with an illustrative embodiment of the present invention. The illustrative user environment is similar to the prior art user environment shown in  FIG. 2 , but includes illustrative handset  32 , which is similar to prior art handset  22  of  FIG. 2  but has been modified in accordance with this illustrative embodiment of the present invention. 
         [0023]    Specifically, the illustrative user environment of  FIG. 3  includes Bluetooth (BT) headset  21 , wirelessly connected (shown as direct arrowed connections for ease of understanding signal flow) to illustrative handset  32 , which is in turn connected to VoIP network  24 . In particular, illustrative handset  32  includes therein Bluetooth (BT) chipset  33  to support the use of BT headset  21 . Specifically, note that BT chipset  33 , in addition to comprising BT receiver  231 , audio decoder  232 , audio encoder  233 , and BT transmitter  234  (as does prior art BT chipset  23 ), advantageously also comprises BT-to-RTP packetization module  331  and RTP-to-BT packetization module  332  for use in performing high quality speech communication across the VoIP communications network in accordance with this illustrative embodiment of the present invention. Note that illustrative handset  32  (like prior art handset  22 ) may be either a mobile handset (in which case VoIP network  24  comprises, at least in part, a wireless IP network, and wherein handset  32  is wirelessly connected thereto) or a wired handset (in which case VoIP network  24  comprises, at least in part, a wired IP network, and wherein handset  32  is connected thereto via a wired connection). 
         [0024]    As in the prior art user environment shown in  FIG. 2 , BT headset  21  of the illustrative user environment of  FIG. 3  comprises microphone  211 , audio encoder  212 , BT transmitter  213 , BT receiver  214 , audio decoder  215 , and loudspeaker  216 . However, unlike prior art handset  22 , illustrative handset  32  comprises speech encoder  221 , VoIP packetization module  222 , RTP transmitter and receiver  223 , jitter buffer  224 , and speech decoder  225  (as does prior art handset  22 ), but also includes BT chipset  33  rather than BT chipset  23 . Specifically, BT chipset  33 , a modified version of prior art BT chipset  23 , comprises BT receiver  231 , audio decoder  232 , audio encoder  233 , and BT transmitter  234  (as does prior art BT chipset  22 ), but also advantageously includes BT-to-RTP packetization module  331  and RTP-to-BT packetization module  341 . 
         [0025]    In operation in the “forward” direction when BT headset  21  is being used (i.e., for transmitting speech across the VoIP network when the BT headset user is speaking), illustrative handset  32  may operate in a conventional manner, wherein BT receiver  231  wirelessly receives the BT signal, audio decoder  232  decompresses the signal back into an audio waveform, speech encoder  221  (re-)compresses this audio waveform, and VoIP packetization module  222  converts the encoded speech signal into IP packets, as does prior art handset  22  (as described in connection with the prior art user environment of  FIG. 2  above). However, in accordance with the principles of the present invention and in accordance with an illustrative embodiment thereof, a “premium” mode of operation is available to illustrative handset  32  whereby high quality speech communication may be advantageously performed therein. 
         [0026]    Specifically, when BT headset  21  is being used in the “forward” direction (i.e., for transmitting speech across the VoIP network when the BT headset user is speaking), illustrative handset  32  may operate in such a “premium” mode (as shown by the heavy arrows in  FIG. 3 ) by advantageously bypassing audio decoder  232 , speech encoder  221 , and VoIP packetization module  222 , and instead employing BT-to-RTP packetization module  331  to advantageously convert the received BT signal (which comprises encoded audio signal packets), as received by BT receiver  231 , directly to RTP packets (which also comprise the encoded audio signal, albeit in a different format—i.e., in RTP format rather than in BT Protocol format) for transmission across VoIP network  24 . In this manner, high quality speech signals are advantageously transmitted across the VoIP network for use by another illustrative handset capable of performing such “premium” mode speech communication. 
         [0027]    Similarly, in operation in the “reverse” direction (i.e., for receiving speech from the VoIP network when the BT headset user is listening), illustrative handset  32  may operate in a conventional manner, wherein RTP transmitter and receiver  223  receives IP packets—typically in Real-time Transport Protocol (RTP) form—which it stores and then reads out of jitter buffer  224 , decompresses with speech decoder  225  to produce an audio waveform, and then (re-)compresses with audio encoder  233  for wireless transmission by BT transmitter  234  to BT headset  21  using a BT protocol, as does prior art handset  22  (as described in connection with the prior art user environment of  FIG. 2  above). However, in accordance with the principles of the present invention and in accordance with an illustrative embodiment thereof, a “premium” mode of operation is available to illustrative handset  32  whereby high quality speech communication may be advantageously performed therein. 
         [0028]    Specifically, when BT headset  21  is being used in the “reverse” direction (i.e., for receiving speech from the VoIP network when the BT headset user is listening), illustrative handset  32  may operate in such a “premium” mode (as shown by the heavy arrows in  FIG. 3 ) by advantageously bypassing speech decoder  225  and audio encoder  233 , and instead employing RTP-to-BT packetization module  332  to advantageously convert the received RTP packets (which comprise encoded audio signal packets, assuming that they have been transmitted across VoIP network  24  by another such illustrative handset operating in “premium” mode), as received from VoIP network  24  (after having been stored and read out from jitter buffer  224 ), directly to BT packets (which also comprise the encoded audio signal, albeit in a different format—i.e., in BT Protocol format rather than in RTP format) for transmission to BT headset  21 . In this manner, high quality audio may be received from another illustrative handset capable of performing such “premium” mode speech communication, and may be advantageously used by illustrative handset  32  and BT headset  21  of the illustrative user environment of  FIG. 3 . 
         [0029]      FIG. 4  shows a flowchart of a method for converting a sequence of Bluetooth Protocol packets to a corresponding sequence of Real-time Transport Protocol (RTP) packets in accordance with an illustrative embodiment of the present invention, along with a sample of the operation of the illustrative method shown therein. In particular, the illustrative method of  FIG. 4  may, for example, be performed by BT-to-RTP packetization module  331  of illustrative handset  32  as shown in the illustrative user environment of  FIG. 3 . 
         [0030]    As shown in the figure, illustrative BT Protocol packet  41  comprises Logical Link Control and Adaptation Protocol (L2CAP) header  411 , followed by Media Packet (MP) header  412 , followed by Contents Protection (CP) header  413 , and then followed by media payload  414 . (As is fully familiar to those of ordinary skill in the art, L2CAP is part of the BT Protocol. Each of the aforementioned headers is also fully familiar to those of ordinary skill in the art.) As is fully familiar to those of ordinary skill in the art, MP header  412  and CP header  413  together comprise the Audio/Visual Data Transport Protocol (AVDTP) header of the BT Protocol packet. And in accordance with the illustrative embodiment of the present invention, media payload  414  advantageously comprises a portion of an encoded audio signal which comprises speech, as illustratively provided, for example, by BT headset  21  of  FIG. 3 . 
         [0031]    In step  46  of the illustrative method, L2CAP header  411  is removed from BT packet  41  to generate modified packet  42  (comprising only MP header  412 , CP header  413  and media payload  414 ). Then, in step  47  of the illustrative method, the AVDTP header (MP header  412  and CP header  413  together) is removed from modified packet  42 —first to generate modified packet  43  (comprising only CP header  413  and media payload  414 ), and then to generate therefrom modified packet  44  (comprising only media payload  414 ). Next, an optional step  48  may or may not be performed in which media payload  414  of modified packet  44  is decrypted. (This step is only performed in the case where media payload  414  has been encrypted prior to its receipt by the illustrative method of  FIG. 4 . As is well known to those skilled in the art, the BT Protocol provides for optional secure communication using conventional encryption techniques.) And finally, in step  49  of the illustrative method, RTP header  415  is added to modified packet  44  to generate RTP packet  45  for transmission across the VoIP network. The illustrative method advantageously repeats for a given sequence of BT Protocol packets input thereto. 
         [0032]      FIG. 5  shows a flowchart of a method for converting a sequence of Real-time Transport Protocol (RTP) packets to a corresponding sequence of Bluetooth Protocol packets in accordance with an illustrative embodiment of the present invention, along with a sample of the operation of the illustrative method shown therein. In particular, the illustrative method of  FIG. 5  may, for example, be performed by RTP-to-BT packetization module  332  of illustrative handset  32  as shown in the illustrative user environment of  FIG. 3 . 
         [0033]    As shown in the figure, illustrative RTP packet  51  comprises RTP header  511  followed by media payload  512 . In accordance with the illustrative embodiment of the present invention, media payload  512  advantageously comprises a portion of an encoded audio signal which comprises speech, as illustratively received from, for example, VoIP network  24  of  FIG. 3 . 
         [0034]    In step  56  of the illustrative method, RTP header  511  is removed from RTP packet  51  to generate modified packet  52  (comprising only media payload  512 ). Next, an optional step  57  may or may not be performed in which media payload  512  of modified packet  52  is encrypted (for purposes of optional secure BT communication—see discussion above). Then, in step  58  of the illustrative method, the AVDTP header (comprising CP header  513  preceded by MP header  514 ) is added to modified packet  52 —first to generate modified packet  53  (comprising CP header  513  and media payload  512 ), and then to generate therefrom modified packet  54  (comprising MP header  514 , CP header  513  and media payload  512 ). Finally, in step  59  of the illustrative method, L2CAP header  515  is added to modified packet  54  to generate BT packet  55  for use in transmission to, for example, BT headset  21  of  FIG. 3 . The illustrative method advantageously repeats for a given, sequence of RTP packets input thereto. 
         [0035]    Finally, note that in accordance with certain illustrative embodiments of the present invention, a “premium” VoIP call may advantageously be initially set up between two parties (e.g., two illustrative handsets implemented in accordance with the principles of the present invention and in accordance with illustrative embodiments thereof), using a slightly modified version of an otherwise fully conventional technique. As is well known to those of ordinary skill in the art, typical VoIP calls have such an “initial” call setup phase in which the characteristics of the speech data to be communicated between the parties to the call is communicated and/or negotiated with and between the network and the intended parties to the call. For example, the specific codec type typically needs to be communicated/negotiated, since only if both parties&#39; handsets support a particular coding scheme (e.g., EVRC, AMR, etc.) will it be possible for them to communicate using that scheme. 
         [0036]    Therefore, in accordance with certain illustrative embodiments of the present invention, at the beginning of a VoIP call which is desired to be performed in a “premium” mode of operation (using the principles of the present invention), the handsets advantageously communicate with the network and each other in order to negotiate such a resource—namely, to ensure that both parties can support such “premium” calls using a common encoding format. For example, if both parties&#39; handsets are being used specifically with BT headsets which use a common audio codec, then they may communicate in accordance with the illustrative embodiment shown and described above in connection with  FIG. 3 . In particular, then, after checking the connectivity to the given BT headset, the specific audio codec information associated with the BT headset may be advantageously included in a network signaling message (i.e., communicated as part of the call setup phase), whenever an initial call request is made in accordance with an illustrative embodiment of the present invention. Then, assuming compatibility, the network advantageously sends confirmatory messages to both handsets to enable the “premium” call mode. 
       Addendum to the Detailed Description 
       [0037]    The preceding merely illustrates the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. 
         [0038]    Thus, for example, it will be appreciated by those skilled in the art that the block diagrams herein represent conceptual views of illustrative circuitry embodying the principles of the invention. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudocode, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown. 
         [0039]    A person of ordinary skill in the art would readily recognize that steps of various above-described methods can be performed by programmed computers. Herein, some embodiments are also intended to cover program storage devices, e.g., digital data storage media, which are machine or computer readable and encode machine-executable or computer-executable programs of instructions, wherein said instructions perform some or all of the steps of said above-described methods. The program storage devices may be, e.g., digital memories, magnetic storage media such as magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media. The embodiments are also intended to cover computers programmed to perform said steps of the above-described methods. 
         [0040]    The functions of any elements shown in the figures, including functional blocks labeled as “processors” or “modules” may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Moreover, explicit use of the term “processor” or “controller” should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, read only memory (ROM) for storing software, random access memory (RAM), and non volatile storage. Other hardware, conventional and/or custom, may also be included. Similarly, any switches shown in the figures are conceptual only. Their function may be carried out through the operation of program logic, through dedicated logic, through the interaction of program control and dedicated logic, or even manually, the particular technique being selectable by the implementer as more specifically understood from the context. 
         [0041]    In the claims hereof any element expressed as a means for performing a specified function is intended to encompass any way of performing that function including, for example, a) a combination of circuit elements which performs that function or b) software in any form, including, therefore, firmware, microcode or the like, combined with appropriate circuitry for executing that software to perform the function. The invention as defined by such claims resides in the fact that the functionalities provided by the various recited means are combined and brought together in the manner which the claims call for. Applicant thus regards any means which can provide those functionalities as equivalent as those shown herein.