Patent Publication Number: US-8538397-B2

Title: System and method for in-band modem to modem communication

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/445,437, filed Apr. 12, 2012, which is a continuation of U.S. patent application Ser. No. 12/754,790, filed Apr. 6, 2010 and entitled “SYSTEM AND METHOD FOR IN-BAND MODEM TO MODEM COMMUNICATION” now U.S. Pat. No. 8,180,331, all of which are hereby incorporated by reference in its entirety. 
    
    
     FIELD 
     The present application relates generally to mobile communication devices and, more particularly to systems and methods for in-band modem to modem communications during voice communication sessions. 
     BACKGROUND 
     Technology exists for routing communications originating from a wireless handheld telephony device through a server such as an enterprise server. This can be done, for example, to make it appear as if the communication originated from a user&#39;s place of business or to prevent a party receiving the communication from accessing the wireless user&#39;s wireless number. Often, such communications will use both an audio or voice channel for relaying a voice communication and a data channel for, for example, sending control information between the server and the wireless handheld telephony device. For example, the server may send a control command to the wireless handheld telephony device informing it of an incoming communication. Similarly, the wireless handheld telephony device may send a control command to the server requesting that the current communication be put on hold. These control commands may be sent via the a data channel when such a channel is available. 
     In some situations, however, a data channel between the wireless handheld telephony device and the server may be permanently or temporarily unavailable. Some current systems use means such as DTMF transmission/detection, data over SMS, USSD, etc. for relaying control or other data when a data channel is unavailable. The use of DTMF protocols and devices for non-audio signalling, however, can be slow, and creates issues concerning both missing tones and false detection of tones and is generally limited. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made, by way of example, to the accompanying drawings which show example embodiments of the present application, and in which: 
         FIG. 1  shows a schematic diagram of an example system suitable for use in managing telephone and other communications in accordance with the disclosure herein; 
         FIGS. 2-4  show schematic diagrams of examples of embodiments of details of a system such as that shown in  FIG. 1 ; 
         FIG. 5  shows a schematic block diagram of a wireless handheld telephony device  11  suitable for use in conjunction with the system of  FIG. 1 ; 
         FIG. 6  shows a schematic diagram of an example of a system suitable for use in managing telephone and other communications in accordance with the disclosure herein; 
         FIG. 7  shows a schematic flow diagram of an example of a method of transmitting a data message from a call control server to a wireless handheld telephony device suitable for use in implementing various embodiments of the disclosure; and 
         FIG. 8  shows a schematic flow diagram of an example of a method of transmitting a data message from a wireless handheld telephony device to a call control server according to an embodiment. 
     
    
    
     Similar reference numerals may have been used in different figures to denote similar components. 
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     In one aspect, the present disclosure provides a system for controlling communications between a call control server, a wireless handheld telephony device, and at least one second telephony device, the system comprising a data processor, media readable by the data processor, and a communications system; the communications system adapted to process signals sent between the wireless handheld telephony device, the at least one second telephony device, and the data processor; and the media readable by the data processor comprising coded program instructions adapted to cause the processor to: transmit modulated control signals to the wireless handheld telephony device through the audio channel of a leg of a communication session previously established between the wireless handheld telephony device and at least one second telephony device; and upon receipt of modulated response signals from the wireless handheld telephony device, transmit the modulated response signals to a modem in communication with the call control server. 
     In another aspect, the present disclosure provides a method enabling a system to transmit signals representing data to and from a wireless handheld telephony device through an audio channel of a first call leg of a communication session previously established between the wireless handheld telephony device and at least one second telephony device, the communication session being controlled by a call control server, the system comprising a data processor, media readable by the data processor and a communications subsystem, the communications subsystem adapted to process signals representing communications by and between the wireless handheld telephony device, the at least one second telephony device, the call control server and the processor and the media readable by the data processor comprising coded program instructions, the method comprising: upon receipt of modulated control signals representing one or more data messages from the call control server, transmitting the modulated control signals to the wireless handheld telephony device through the audio channel of the first call leg; and upon receipt of modulated response signals representing one or more data messages from the wireless handheld telephony device, transmitting the modulated response signals to a modem device in communication with the call control server. 
     Other aspects of the present disclosure will be apparent to those skilled in the relevant arts from a review of the following detailed description in conjunction with the drawings. 
     Embodiments of the present application are not limited to any particular operating systems, wireless handheld telephony device architectures, server architectures, or computer programming languages. 
     Reference is now made to  FIG. 1 , which shows, in block diagram form, an example of a system, generally designated  10 , for the control and management of communications, suitable for use in implementing systems and methods disclosed herein. System  10  includes an enterprise or business communications system  20 , which may include a local area network (LAN). In the description below, the enterprise or business system  20  may be referred to as an enterprise network  20 . It will be appreciated that the enterprise network  20  may include more than one network and may be located in multiple geographic areas in some embodiments. 
     The enterprise network  20  may be connected, for example through a firewall  22 , to a wide area network (WAN)  30 , such as the Internet. The enterprise network  20  may also be connected to a public switched telephone network (PSTN)  40  via direct inward dialing (DID) trunks or primary rate interface (PRI) trunks. 
     The enterprise network  20  may also communicate with a public land mobile network (PLMN)  50 , which may also be referred to as a wireless wide area network (WWAN) or, in some cases, a cellular network. Connection with the PLMN  50  may be made via a relay  26 , as known in the art. 
     The enterprise network  20  may also provide one or more wireless local area networks (WLANs)  32   a  featuring wireless access points. Other WLANs  32  may exist outside the enterprise network  20 . For example, WLAN  32   b  may be connected to WAN  30 . 
     System  10  may include and/or interact with a number of enterprise-associated mobile devices  11  (only one shown). Mobile device(s)  11  may include devices equipped for cellular communication through the PLMN  50 , mobile devices equipped for Wi-Fi communications over one of the WLANs  32 , and/or dual-mode devices capable of both cellular and WLAN communications. WLANs  32  may be configured in accordance with one of the IEEE 802.11 specifications. 
     It will be understood that mobile devices  11  typically include one or more radio transceivers and associated processing hardware and software to enable wireless communications with the PLMN  50  and/or one or more WLANs  32 . In various embodiments, PLMN  50  and mobile devices  11  may be configured to operate in compliance with any one or more of a number of wireless protocols, including GSM, GPRS, CDMA, EDGE, UMTS, EvDO, HSPA, 3GPP, or a variety of others. It will be appreciated that a mobile device  11  may roam within the PLMN  50  and across PLMNs, in for example any of a variety of known manners, as the user moves. In some instances, the dual-mode mobile devices  11  and/or the enterprise network  20  are configured to facilitate roaming between the PLMN  50  and a WLAN  32 , and are thus capable of seamlessly transferring sessions (such as voice calls) from a connection with the cellular interface of the dual-mode device  11  to the WLAN  32  interface of the dual-mode device  11 , and vice versa. 
     Enterprise network  20  typically includes a number of networked servers, computers, and other devices. For example, the enterprise network  20  may connect one or more desktop or laptop computers  15  (one shown). The connection may be wired or wireless in some embodiments. The enterprise network  20  may also connect to one or more digital telephone sets  17  (one shown). 
     The enterprise network  20  may include one or more mail servers, such as mail server  24 , for coordinating the transmission, storage, and receipt of electronic messages for client devices operating within the enterprise network  20 . Typical mail servers include the Microsoft Exchange Server™ and the IBM Lotus Domino™ server. Each user within the enterprise typically has at least one user account within the enterprise network  20 . Associated with each user account is message address information, such as an e-mail address. Messages addressed to a user message address are stored on the enterprise network  20  in the mail server  24 . The messages may be retrieved by the user using a messaging application, such as an e-mail client application. The messaging application may be operating on a user&#39;s computer  15  connected to the enterprise network  20  within the enterprise. In some embodiments, the user may be permitted to access stored messages using a remote computer, for example at another location via the WAN  30  using a VPN connection. Using the messaging application, the user may also compose and send messages addressed to others, within or outside the enterprise network  20 . The messaging application causes the mail server  24  to send a composed message to the addressee, often via the WAN  30 . 
     Relay  26  serves to route messages received over the PLMN  50  from the mobile device  11  to the corresponding enterprise network  20 . Relay  26  also pushes messages from the enterprise network  20  to the mobile device  11  via the PLMN  50 . 
     In the embodiment shown, enterprise network  20  also includes an enterprise server  12 . Together with the relay  26 , the enterprise server  12  can function to redirect, copy, or relay incoming e-mail messages addressed to a user&#39;s e-mail address within the enterprise network  20  to the user&#39;s mobile device  11  and to relay incoming e-mail messages composed and sent via the mobile device  11  out to the intended recipients within the WAN  30  and/or elsewhere. Among other functions, enterprise server  12  and relay  26  together can facilitate “push” e-mail service for the mobile device  11  enabling the user to send and receive e-mail messages using the mobile device  11  as though the user were connected to an e-mail client within the enterprise network  20  using the user&#39;s enterprise-related e-mail address, for example on computer  15 . 
     As is typical in many enterprises, an enterprise network  20  can include one or more Private Branch eXchanges (although in various embodiments the PBX(s) may include standard PBX(s) or IP-PBX(s), for simplicity the description below uses the term PBX to refer to both)  16  having a connection with the PSTN  40  for routing incoming and outgoing voice calls to and from digital and/or analog telephones or other telephony devices for the enterprise. PBX  16  is connected to the PSTN  40  via DID trunks or PRI trunks, for example. The PBX  16  may use ISDN signaling protocols for setting up and tearing down circuit-switched connections through the PSTN  40  and related signaling and communications. In some embodiments, PBX  16  may be connected to one or more conventional analog telephones  19 . The PBX  16  may also be connected to the enterprise network  20  and, through it, to telephone terminal devices, such as digital telephone sets  17 , softphones operating on computers  15 , etc. Within the enterprise, each individual may have an associated extension number, sometimes referred to as a PNP (private numbering plan), or direct dial phone number. Calls outgoing from the PBX  16  to the PSTN  40  or incoming from the PSTN  40  to the PBX  16  are typically circuit-switched calls. Within the enterprise, e.g. between the PBX  16  and terminal devices, voice calls are often packet-switched calls, for example Voice-over-IP (VoIP) calls. 
     Enterprise network  20  may include a Service Management Platform (SMP)  18  for performing aspects of messaging or session control, such as call control and advanced call processing features. SMP  18  may, in some cases, also perform some media handling. Collectively SMP  18  and PBX  16  may be referred to as a enterprise communications platform, generally designated  14 . It will be appreciated that an enterprise communications platform  14  and, in particular, an SMP  18 , can be implemented on one or more servers having suitable communications interfaces for connecting to and communicating with the PBX  16  and/or DID/PRI trunks. Although the SMP  18  may be implemented on a stand-alone server, it will be appreciated that it may be implemented into an existing control agent/server as a logical software component. As will be described below, the SMP  18  may be implemented as a multi-layer platform. 
     For devices such as telephony devices  11 ,  19  controlled by or otherwise associated with it, enterprise communications platform  14  can implement switching to connect session legs and may provide conversion between, for example, a circuit-switched call and a VoIP call, or connect legs of other media sessions. Such calls/sessions may be set up and modified on behalf of devices  11 ,  19  and any desired telephony devices, within or outside enterprise network  20 , including for example devices  19 ,  107  connected to PSTN  40 . In some embodiments, in the context of voice calls the enterprise communications platform  14  provides a number of additional functions including automated attendant, interactive voice response, call forwarding, voice mail, etc. It may also implement certain usage restrictions on enterprise users, such as blocking international calls or 1-900 calls. In many embodiments, Session Initiation Protocol (SIP) may be used to set-up, manage, and terminate media sessions for voice calls. Other protocols may also be employed by the enterprise communications platform  14 , for example, Web Services, Computer Telephony Integration (CTI) protocol, Session Initiation Protocol for Instant Messaging and Presence Leveraging Extensions (SIMPLE), and various custom Application Programming Interfaces (APIs), as will be described in greater detail below. 
     Among capabilities of enterprise communications platform  14  may be the ability to extend the features of enterprise telephony to mobile device(s)  11 . For example, an enterprise communications platform  14  may allow mobile device(s)  11  to perform functions akin to those normally available on a standard office telephone, such as the digital telephone set  17  or analog telephone set  15 . Example features may include direct extension dialing, enterprise voice mail, conferencing, call transfer, call park, etc. As further described elsewhere herein, enterprise communications platform  14  may be configured to provide functions such as transfer of corresponding ends of existing communications sessions from one or more mobile devices  11  to wired telephony devices  19  associated with platform  14 . 
     Reference is now made to  FIGS. 2 to 4 , which show example embodiments of the enterprise communications system  14 . Although references are made below to “calls” or call-centric features it will be appreciated that the architectures and systems depicted and described are applicable to session-based (e.g., voice) communications in general and, in some instances, to text, image, or other messaging-based communications. 
       FIG. 2  illustrates an embodiment intended for use in a circuit-switched TDM context. The PBX  16  is coupled to the SMP  18  via PRI connection  60  or other suitable digital trunk. In some embodiments, the PRI connection  60  may include a first PRI connection, a second PRI connection, and a channel service unit (CSU), wherein the CSU is a mechanism for connecting computing devices to digital mediums in a manner that allows for the retiming and regeneration of incoming signals. It will be appreciated that there may be additional or alternative connections between the PBX  16  and the SMP  18 . 
     In such embodiments, an SMP  18  can assume control over both call processing and the media itself. This architecture may be referred to as “First Party Call Control”. Many of the media handling functions normally implemented by the PBX  16  may be handled by the SMP  18  in this type architecture. Incoming calls addressed to any extension or direct dial number within the enterprise, for example, may first be routed to the SMP  18 . Thereafter, a call leg may be established from the SMP  18  to the called party within the enterprise, and the two legs may be bridged. Accordingly, the SMP  18  includes a digital trunk interface  62  and a digital signal processing (DSP) conferencing bridge  64 . The DSP conferencing bridge  64  performs the bridging of calls for implementation of various call features, such as conferencing, call transfer, etc. The digital trunk interface  62  may be implemented as a plurality of telephonic cards, e.g. Intel Dialogic cards, interconnected by a bus and operating under the control of a processor. The digital trunk interface  62  may also be partly implemented using a processor module such as, for example, a Host Media Processing (HMP) processor. 
     SMP  18  may implement various scripts  66  for managing call processing. The scripts  66  may be implemented as software modules, routines, functions, etc., stored in non-volatile memory and executed by the processor of the SMP  18 . Such scripts  66  may implement call flow logic, business logic, user preferences, call service processes, and various feature applications. 
       FIG. 3  shows another embodiment in which the PBX  16  performs the functions of terminating and/or bridging media streams, but call control functions are largely handled by the SMP  18 . In this embodiment, the SMP  18  may be referred to as a call control server  18 . Such an architecture may be referred to as “Third-Party Call Control”. 
     The call control server  18  is coupled to the PBX  16 , for example through the LAN, enabling packet-based communications and, more specifically, IP-based communications. In one embodiment, communications between the PBX  16  and the call control server  18  are carried out in accordance with SIP. In other words, the call control server  18  uses SIP-based communications to manage the set up, tear down, and control of media handled by the PBX  16 . In one example embodiment, the call control server  18  may employ a communications protocol conforming to the ECMA-269 or ECMA-323 standards for Computer Supported Telecommunications Applications (CSTA). 
       FIG. 4  shows yet another embodiment of an enterprise communications system  14 . This embodiment reflects the adaptation of an existing set of call processing scripts to an architecture that relies on third-party call control, with separate call control and media handling. In this embodiment SMP  18  includes a call processing server  74 . The call processing server  74  implements the scripts or other programming constructs for performing call handling functions. SMP  18  can also include an SIP server  72  and a media server  76 . The separate SIP server  72  and media server  76  logically separate call control from media handling functions. SIP server  72  can interact with call processing server  74  using a computer-implemented communications handling protocol, such as one of the ECMA-269 or ECMA-323 standards. These standards prescribe XML-based messaging for implementing Computer Supported Telecommunications Applications (CSTA). 
     SIP server  72  can interact with media server  76  using SIP-based media handling commands. For example, the SIP server  72  and media server  76  may communicate using Media Server Markup Language (MSML) as defined in IETF document Saleem A., “Media Server Markup Language”, Internet Draft, draft-saleem-msml-07, Aug. 7, 2008. The media server  76  may be configured to perform Host Media Processing (HMP). 
     It will be appreciated by those skilled in the relevant arts that a wide variety of architectures or configurations for the enterprise communications system  14  are suitable for use in implementing the systems and methods disclosed herein. 
     Reference is now made to  FIG. 5 , which shows a schematic block diagram of a wireless handheld telephony device  11  suitable for use in conjunction with the system  10  described above in relation to  FIG. 1 . 
     In various embodiments, wireless handheld telephony device  11  is a two-way mobile communication device having at least voice and data communication capabilities, including the capability to communicate with other computer systems. Depending on the functionality(ies) provided by the wireless handheld telephony device  11 , it may be referred to as a data messaging device, a two-way pager, a cellular telephone with data messaging capabilities, a wireless Internet appliance, a data communication device (with or without telephony capabilities), a clamshell device, or a flip-phone. The wireless handheld telephony device  11  may communicate with any one of a plurality of fixed transceiver stations within its geographic coverage area. 
     The wireless handheld telephony device  11  may incorporate a communication subsystem  112 , which can include a receiver  114 , transmitter  116 , and associated components, such as one or more antenna elements  118  and  120 , local oscillators (LOs)  122 , and one or more processing modules such as a digital signal processor (DSP)  124 . In various embodiments, antenna elements  118  and  120  may be embedded or internal to the wireless handheld telephony device  11 . As will be apparent to those skilled in the relevant arts, the particular design of the communication subsystem  112  will depend, in part, on the system(s), such as enterprise network  20 , the PLMN  50  and/or the WLANs  32 , with which the wireless handheld telephony device  11  is intended to communicate. 
     The wireless handheld telephony device  11  may send and receive communication signals to and from, for example, an enterprise server  20  through, for example, the PLMN  50  and/or one of the WLANs  32 . Signals received by the antenna  118  may be input to the receiver  114 , which may perform such common receiver functions as signal amplification, frequency down conversion, filtering, channel selection, etc., as well as analog-to-digital (A/D) conversion. A/D conversion of a received signal allows more complex communication functions such as demodulation and decoding to be performed in the DSP  124 . In a similar manner, signals to be transmitted are processed, including modulation and encoding, for example, by the DSP  124 . Such DSP-processed signals may be input to the transmitter  116  for digital-to-analog (D/A) conversion, frequency up conversion, filtering, amplification, and transmission via the antenna  120 . The DSP  124  not only processes communication signals, but also provides for receiver and transmitter control. For example, gains applied to communication signals in the receiver  114  and the transmitter  116  may be adaptively controlled through automatic gain control algorithms implemented in or by the DSP  124 . 
     Network access may be associated with a subscriber or user of the wireless handheld telephony device  11  via a memory module, such as a memory module  130 , which may include a Subscriber Identity Module (SIM) card for use in a GSM network or a Universal Subscriber Identity Module (USIM) card for use in a Universal Mobile Telecommunication System (UMTS). Such a SIM card may be inserted in or connected to an interface  132  of the wireless handheld telephony device  11 . Alternatively, or in addition, the wireless handheld telephony device  11  may have an integrated identity module for use with systems such as Code Division Multiple Access (CDMA) systems. 
     The wireless handheld telephony device  11  may also include a battery interface  136  for receiving one or more rechargeable batteries  138 . The battery  138  provides electrical power to at least some of the electrical circuitry in the wireless handheld telephony device  11 , and the battery interface  136  provides a mechanical and electrical connection for the battery  138 . The battery interface  136  is coupled to a regulator (not shown) which provides power V+ to the circuitry of the wireless handheld telephony device  11 . 
     Wireless handheld telephony device  11  can include one or more microprocessors  140  for control of the overall operation of the wireless handheld telephony device  11 . for example, under control of mircroprocessor(s)  140  communication functions, including at least data and voice communications, may performed through the communication subsystem  112 . Microprocessor(s)  140  may also interact with additional device subsystems such as modem  128 , primary display  142 , optional secondary display  143 , flash memory  144 , random access memory (RAM)  146 , read-only memory (ROM)  148 , auxiliary input/output (I/O) subsystems  150 , data port(s) such as Universal Serial Bus (USB) port  152 , keyboard or keypad  154 , speaker or audio port(s)  156  for connecting to, for example a set of headphones or an earpiece, microphone  158 , clickable thumbwheel or thumbwheel  160 , open/close sensor  161 , short-range communications subsystem  162 , and any other device subsystem(s) generally designated as  164 . Some of the subsystems shown in  FIG. 5  perform communication-related functions, whereas other subsystems may provide “resident” or on-device functions. Notably, some subsystems, such as the keypad  154 , the primary display  142 , the secondary display  143 , and the clickable thumbwheel  160 , for example, may be used for both communication-related functions, such as displaying notifications or entering a text message for transmission through, for example, the PLMN  50  and/or one of the WLANs  32 , and executing device-resident functions such as a clock, a calculator or a task list. Operating system software used by the microprocessor  140  is preferably stored in a persistent store such as the flash memory  144 , which may alternatively be the ROM  148  or similar storage element. Those skilled in the art will appreciate that the operating system, specific device applications, or parts thereof, may be temporarily loaded into a volatile store such as the RAM  146 . 
     Microprocessor  140 , in addition to its operating system functions, may enable execution of software applications on the wireless handheld telephony device  11 . A predetermined set of applications that control basic device operations, including data and voice communication applications, will normally be installed on the wireless handheld telephony device  11  during or after manufacture. The wireless handheld telephony device  11  may include a personal information manager (PIM) application having the ability to organize and manage data items relating to a user such as, but not limited to, instant messaging, email, calendar events, voice mails, appointments, and task items. One or more memory stores may be available on the wireless handheld telephony device  11  to facilitate storage of information, such as the flash memory  144 , the RAM  146 , the ROM  148 , the memory module  130 , or other types of memory storage devices or FLASH memory cards represented by the other device subsystems  164 , such as Secure Digital (SD) cards or mini SD cards, etc. 
     PIM and/or media applications may have the ability to implement sending and receiving of data items via PLMN  50  and/or one of the WLANs  32  or via a link to a computer system. Suitable communications links to involved computer systems may be established via a serial port  152  and/or a short-range communications subsystem  162 . In some embodiments, PIM and/or media data items are seamlessly combined, synchronized, and updated, for example, through the PLMN  50  and/or one of the WLANs  32 , with the wireless handheld telephony device user&#39;s corresponding data items stored and/or associated with a host computer system thereby creating a mirrored or partially mirrored host computer on the wireless handheld telephony device  11  with respect to such items. This may be advantageous where, for example the host computer system is the wireless handheld telephony device user&#39;s office computer system. Additional applications may also be loaded onto the wireless handheld telephony device  11  through, for example, the PLMN  50  and/or one of the WLANs  32 , the auxiliary I/O subsystem  150 , the serial port  152 , the short-range communications subsystem  162 , or any other suitable subsystem  164 , and installed by a user in the RAM  146  or a non-volatile store such as the ROM  148  for execution by the microprocessor  140 . Such flexibility in application installation increases the functionality of the wireless handheld telephony device  11  and may provide enhanced on-device functions, communication-related functions, or both. For example, secure communication applications may enable electronic commerce functions and other such financial transactions to be performed using the wireless handheld telephony device  11 . 
     In a data communication mode, a received data signal representing information such as a text message, an email message, a media file to be transferred, or Web page download can be processed by the communication subsystem  112  and input to the microprocessor  140 . The microprocessor  140  can further process the signal for output to the primary display  142 , secondary display  143 , or alternatively to the auxiliary I/O device  150 . A user of the wireless handheld telephony device  11  may also compose data items, such as email messages, for example, using the keypad  154  and/or the clickable thumbwheel  160  in conjunction with the primary display  142  and possibly the auxiliary I/O device  150 . The keypad  154  maybe either a complete alphanumeric keypad or telephone-type keypad. These composed items may be transmitted through the communication subsystem  112  or via the short range communication subsystem  162 . 
     For voice communications, the overall operation of the wireless handheld telephony device  11  is similar, except that the received signals may be output to the speaker or audio port  156  and signals for transmission can be generated by a transducer such as the microphone  158 . Alternative voice or audio I/O subsystems, such as a voice message recording subsystem, may also be implemented on the wireless handheld telephony device  11 . Although voice or audio signal output is typically accomplished primarily through the speaker or audio port  156 , the primary display  142  or the secondary display  143  may also be used to provide an indication of the identity of a calling party or the communication type, duration of a voice call, or other voice call related information. Stereo headphones or an earpiece may also be used in place of the speaker  156 . 
     USB port  152  is normally implemented in a personal digital assistant (PDA) type communication device for which synchronization with a user&#39;s computer is a desirable, albeit optional, component. USB port  152  can enable a user to set preferences through an external device or software application and can extend the capabilities of the wireless handheld telephony device  11  by providing for information or software downloads to the wireless handheld telephony device  11  other than through the PLMN  50  and/or one of the WLANs  32 . The alternate download path may, for example, be used to load software or data files onto the wireless handheld telephony device  11  through a direct, reliable and trusted connection. 
     Short-range communications subsystem  162  is an additional optional component which can provide for communication between the wireless handheld telephony device  11  and different systems or devices, which need not necessarily be similar devices. For example, the subsystem  162  may include an infrared device and associated circuits and components, or a wireless bus protocol compliant communication mechanism such as a Bluetooth™ communication module to provide for communication with similarly-enabled systems and devices (Bluetooth™ is a registered trademark of Bluetooth SIG, Inc.). In further embodiments, the short-range communications subsystem  162  may include a wireless networking communications subsystem, conforming for example to IEEE 802.11 standards such as one or more of 802.11b, 802.11g, and/or 802.11n. 
     Modem device  128  may, for example, comprise a low-bandwidth modem which can modulate and demodulate data signals to be transmitted over a voice channel. For example, the modem could be a high speed, low-bandwidth modem such as, for example, the 3GPP modem (TS 26.267 or TS 26.268). The modem may also comprise a coder/decoder (also referred to as a codec). 
     Reference is now made to  FIG. 6  which shows, in schematic block diagram form, an example of a system  700  suitable for transmitting data to a wireless handheld telephony device  11  in accordance with this disclosure. In the example shown, system  700  comprises, or is configured to operate in conjunction with, a wireless handheld telephony device  11  which may for example be engaged in an ongoing or otherwise previously-established communication session with one or more second telephony device(s)  750  through a gateway  712 . Second telephony device(s)  750  may include telephony device(s) such as, for example, digital telephony device(s)  19 , analogue telephony device(s)  17 , and/or other wireless handheld telephony device(s)  11 . Second telephony device(s)  750  may include any telephony device(s), wireline or wireless, suitable for use in cojunction with the systems and methods disclosed herein. 
     Gateway  712  facilitates communication between the wireless handheld telephony device  11  and one or more second telephony device(s)  750 . Gateway  712  may include or comprise component(s) such as, for example, a PBX  16  as well as a communication network such as PSTM  40  or PLMN  50  of  FIG. 1 . Gateway  712  may, for example, be incorporated as a part of an enterprise system, or may be hosted by a wireline or wireless carrier. 
     A communication session between the wireless handheld telephony device  11  and the second telephony device(s)  750  may include two call legs: a first call leg  711  between the wireless handheld telephony device  11  and the gateway  712 , and a second call leg  713  between the gateway  712  and each of second telephony device(s)  750 . Each call leg may comprise at least an audio stream to and from the gateway  712 , and optionally one or more control signal streams. The gateway  712  may anchor each call leg at a location that is controllable by the call control server  704 , and may transfer or otherwise direct voice and other data signals from one call leg to another call leg. This may be performed, for example, using Session Description Protocol (SDP, RFC 2327) Shuffling. 
     In some embodiments, a call control server  704  may be employed to facilitate and control the communication session between the two call legs. For example, when an internal call is made from a corporate desk phone (illustrated here as second telephony device  750 ) to an employee&#39;s cellular phone  11 , the corporate desk phone  750  may dial only the internal extension of the cell phone user. The call control server may convert the internal number to an external cellular phone number or use outside an enterprise environment. 
     A call control server  704  may manipulate call legs via a media path manager  702 . For example, the media path manager  702  may be used to request that pairs or other sets of call legs be joined together in order to connect an end-to-end call. Call control server  704  and media path manager  702  may, for example, form part of an SMP  18  of  FIG. 1 . Functions of a call control server  702  may be provided by, for example, various components of an enterprise communications platform  14  shown in  FIG. 1  and described above. 
     For many cellular technologies, such as CDMA 1x, EVDO, GSM, GPRS/EDGE, etc., once a voice communication is established, maintenance of a data channel between the call control server  704  and the wireless handheld telephony device  11  is commonly discontinued. Without a data channel, messages such as control messages to be transmitted to and from a wireless handheld telephony device  11 , such as, for example, in-call feature execution instructions (e.g., hold, dial new number for conference, call waiting, etc.), must be transmitted by some other means such as via an audio channel in use for transmission of call content signals. The system  700  may use a modem device  714  to provide communication between the call control server  704  and the wireless handheld telephony device  11  using the audio channel. The use of a modem to send data via an audio channel may introduce noise to the ongoing communication for short periods of time (e.g. tenths of a second). In contrast, it can take three to four seconds to pass a ten digit number using DTMF tones. 
     A media server  710  may connect a modem device  714  to a gateway  712  by, for example, constructing a third call leg. In some embodiments, the modem device  714  may be implemented as a function on the media server  710 . 
     A modem device  714  can comprise a modem  706 , such as a low-bandwidth duplex modem, and optionally a coder/decoder (also referred to as a codec)  708 . Codec  708  may for example comprise an encoder  720  for encoding an outgoing signal into a format that is acceptable for processing by, for example, media server  710  (such as, for example, AMR, G.711, G.729, G.722, etc.) and a decoder  722  for decoding incoming signals. 
     The modem  706  may comprise a modulator  716  and a demodulator  718 . Modem  706  may be a high speed (e.g. &gt;400 B/s) low bandwidth voice modem, which may be designed to provide reliable delivery on compressed voice/wireless audio channels. In some embodiments, a modem  706  may use two different clocks, an uplink clock  726  for the uplink data path and a downlink clock  724  for the downlink data path, which may help ensure that signalling in both directions can occur simultaneously. For example, the clocks  724 ,  726  may be used to ensure that the modulation is performed at different frequencies for the uplink and downlink, thus providing duplex communications. 
     Modulated signals transmitted from the wireless handheld telephony device along the first call leg may be received by gateway  712  and passed to modem device  714  through the media server  710 . Such modulated signals may then be decoded by the decoder  722  of the codec  708 , passed through the demodulator  718  of the modem  706  and delivered to the call control server  704 . Similarly, signals transmitted from the call control server  704  may be passed through the modulator  716  of the modem  706 , encoded by the encoder  720  of the codec  708 , passed to the media server  710  and transmitted to the wireless handheld telephony device  11  by the gateway  712  along the first call leg. Data messages are sent when a path is available, for example, when where the first call leg is appropriately connected to the modem device  714 . On the downlink, that is, the path from the call control server  704  to the wireless handheld telephony device  11 , to ensure data messages are sent when a path is available, the media path manager  702  may operate a gate  728  that is open when the path is available. In some embodiments, if a message to be sent from the wireless handheld telephony device  11  is in response to a message from the call control server  704  (e.g. a synchronous command), a path may be available. Alternatively or where a command from the wireless handheld telephony device  11  is asynchronous (e.g. not sent in response to a command from the call control server  704 ), a request, such as a DTMF-coded instruction signal, may be sent by the wireless handheld telephony device  11  before a data message is sent as explained below. 
     A modem device  128  of the wireless handheld telephony device  11  (e.g., see  FIG. 5 ) may comprise a similar codec and modem, thus allowing the decoding/demodulation of control messages to the wireless handheld telephony device  11  and the encoding/modulation of response messages from the wireless handheld telephony device  11 . 
     Among other services, a media server  710  may provide conferencing capabilities. In some embodiments, for example, a conference bridge may be established for each communication between a wireless handheld telephony device  11  and a second telephony device  750 , such that a third call leg is established between the gateway  712  and the modem device  714 . In such embodiments, data messages may be sent and received between the call control server  704  and the wireless handheld telephony device  11  through the modem device  714  at any time. 
     In other embodiments, a conference bridge may be established by the media server  710  when data is to be transmitted between the wireless handheld telephony device  11  and the call control server  704 . In such embodiments, if a message is to be transmitted from the call control server  704  to the wireless handheld telephony device  704 , the media path manager  702  may send a request to the media server  710  to establish a conference bridge. Once the message has been transmitted through the modem device  714 , the media server  710  may disable the conference bridge. If a message is to be transmitted from the wireless handheld telephony device  11  to the call control server  704 , an instruction signal, such as one or more suitably-configured DTMF tone(s), may be sent from the wireless handheld telephony device  11 . This signal may for example indicate to the media server  710  that a conference bridge is requested. Once a conference bridge has been established, the wireless handheld telephony device  11  may transmit any desired modulated signals representing messages to be transmitted to the call control server  704  via the modem device  714 . Once such modulated signals have been sent, the media server  710  may disable the conference bridge. 
     In further embodiments, data may be transmitted by temporarily swapping communications to a third call leg. In such embodiments, when a data message is to be transmitted between the wireless handheld telephony device  11  and the call control server  704 , the second call leg between the gateway  712  and the second telephony device  750  may be temporarily disconnected or otherwise suspended by the gateway  712 , and a third call leg between the gateway  712  and the modem device  714  may be temporarily established. Once the data has been transmitted, the third call leg may be disconnected and the second call leg between the wireless handheld telephony device  11  and the second telephony device  750  may be re-established. This may require a break in the communication between the wireless handheld telephony device  11  and the second telephony device  750  of, for example, a few hundred milliseconds. As no conferencing is required in such embodiments, the media server  710  may not be required. 
     Reference is next made to  FIG. 7 , which shows a flow diagram representing an example of a method  800  for transmitting data from a processor such as a call control server  704  to a wireless handheld telephony device  11  engaged in an ongoing communication session with a second telephony device  750 . Embodiments of method  800  are suitable for use, for example, in conjunction with systems  10 ,  700  of  FIGS. 1  and/or  6  and wireless handheld telephony device(s)  11  of  FIG. 5  in implementing aspects of the disclosure herein. 
     A method  800  can be considered to begin at block  802  where a call control server  704  has a message in the form of signals representing data to be transmitted to a wireless handheld telephony device  11  while the wireless handheld telephony device  11  is engaged in an ongoing communication with a second telephony device  750 , for example through a gateway  712 . For example, the call control server  704  may wish to send a message to the wireless handheld telephony device  11  when a second incoming call for the wireless handheld telephony device  11  is received. In some situations, no data connection exists between the call control server  704  and the wireless handheld telephony device  11 . As explained herein, the data may instead be sent in-band via the audio channel using modulated data signals. 
     At  804 , it may be determined whether or not a path is available between the modem device  714  and the gateway  712 . 
     If a path is available at  804 , the method  800  proceeds to  810  where the data is modulated. As explained above, there are a number of different ways in which the transmission of data between the call control server  704  and the wireless handheld telephony device  11  may be facilitated. For example, in some embodiments, a conference bridge may be established by, for example, a media server  710 , for each communication involving the wireless handheld telephony device  11 . In other words, a third call leg may be established to the modem device  714  from the gateway  712 . In such embodiments, a path will be available at  804  and the method  800  continues from block  804  to block  810 . In other embodiments, a path will always be available at  804  and the method  800  always always continues from block  804  to block  810 . 
     If, however, a path is determined not to be available at  804 , at  806  a suitable path is established. For example, in some embodiments, a temporary conference bridge may be established by, for example, a media server  710 , when a message is to be sent between the call control server  704  and the wireless handheld telephony device  11 . In such embodiments, a path may not be available at  804  and may need to be established at  806 . Where the message originates from the call control server  704 , the call control server  704  may notify the media path manager  702  to send a request to the media server  710  to establish a conference bridge. Once the conference bridge is established, creating a path between the modem device  714  and the gateway  712 , the media server  710  may send a notification back to the media path manager  702  that the path is available. 
     In other embodiments, a path may be established between the modem device  714  and the wireless handheld telephony device  11  by creating a temporary call leg between the modem device  714  and the gateway  712  and temporarily disconnecting or otherwise suspending the second call leg from the gateway  712  to the second telephony device  750 . In such embodiments, a path may not be available at  804  and may need to be established at  806 . Where the message originates from the call control server  704 , the call control server  704  may notify the media path manager  702  to send a request to media server  710  through the gateway  712  to establish the third call leg. Once the third call leg is established to the modem device  714  and the second call leg to the second telephony device  750  is temporarily suspended, the gateway  712  may send a notification to the media path manager  702  that the path is available. 
     Once a path is established at  806 , a gate  728  may be opened by the media path manager  702  at  808 , allowing data to flow from the call control server  704  to the modem  706 . Once the gate has been opened at  808 , the method  800  proceeds to block  810 . 
     At  810 , data from the call control manager  704  may be modulated by a modem  706  into signals which may be transmitted via an audio stream. At  812 , the modulated data may be encoded by an encoder  720  into an appropriate format (such as, for example, AMR, G.711, G.729, G.722, etc.). 
     At  814  modulated/encoded data may be sent to the gateway  712  to be transmitted to the wireless handheld telephony device through the voice connection between the gateway  712  and the wireless handheld telephony device  11 . The data may then by decoded (if necessary) and demodulated by a modem device  128  associated with the wireless handheld telephony device  11  at  816 . 
     In some embodiments, a path between modem device  714  and gateway  712  may need to be closed at  818  once data has been sent to the wireless handheld telephony device  11 . For example, where a temporary conference bridge has been established in order to facilitate the communication, this conference bridge may be disabled by, for example, the media server  710 , once the message has reached the gateway  712 . In other embodiments, where a temporary call leg has been established to the modem device  714 , as explained above, the temporary call leg may be disabled and the second call leg to the second telephony device  750  may be re-established at  818 . In either case, at  820 , the gate  728  may be closed in order to prevent data from being sent from the call control server  704  until a new path is established. In some embodiments, where a response is expected from the wireless handheld telephony device  11 , the path may remain open until the response is received. 
     Reference is next made to  FIG. 8 , which shows a flow diagram representing an example of a method  900  for transmitting data from a wireless handheld telephony device  11  to a call control server  704  where the wireless handheld telephony device  11  is engaged in an ongoing communication with a second telephony device  750 . Method  900  is suitable for use, for example, in conjunction with systems  10 ,  700  of  FIGS. 1  and/or  6  and wireless handheld telephony device  11  of  FIG. 5  in implementing the disclosure herein. 
     A method  900  can be considered to begin at block  902  where a wireless handheld telephony device  11  has a message in the form of signals representing data to be transmitted to a call control server  704  and the wireless handheld telephony device  11  is engaged in an ongoing communication with a second telephony device  750  through a gateway  712 . For example, where the wireless handheld telephony device  11  has been informed that a second incoming communication is pending, the wireless handheld telephony device  11  may wish to send a suitably-configured instruction signal to the call control server  704  as to whether the second incoming communication should be accepted or rejected. As explained above, in some situations, no data connection exists between the call control server  704  and the wireless handheld telephony device  11 . As explained herein, data may instead be sent in-band via the audio channel using modulated data signals. 
     At  904 , it is determined whether or not a path is available between the modem device  714  and the wireless handheld telephony device  11 . 
     If a path is available at  904 , the method  900  proceeds to  910  where the data is modulated/encoded. Again, as explained above, there are a number of different ways in which the transmission of data between the call control server  704  and the wireless handheld telephony device  11  may be facilitated. For example, in some embodiments, a conference bridge may be established by, for example, a media server  710 , for each communication involving the wireless handheld telephony device  11 . In other words, a third call leg may be established to the modem device  714  from the gateway  712 . In such embodiments, a path will always be available at  904  and the method  900  always continues from block  904  to block  910 . 
     A path may also be available at  904  in other situations, such as when the media server  710  leaves the path open in anticipation of a response from the wireless handheld telephony device  11 . 
     If, however, a path is determined not to be available at  904 , the method  800  proceeds to block  806  where a path is established. For example, in some embodiments, a temporary conference bridge may be established by, for example, a media server  710 , when a message is to be sent between the call control server  704  and the wireless handheld telephony device  11 . In such embodiments, a path may not be available at  904  and may need to be established at  906 . Where the message originates from the wireless handheld telephony device  11 , the wireless handheld telephony device  11  may need to notify the media server  710  that a message is forthcoming. This may be done, for example, by sending an initiating signal to the gateway  712  which may in turn notify the media server  710  that a conference bridge is required. The initiating signal may, for example, be in the form of a tone, such as a DTMF tone. Once the conference bridge is established, creating a path between the modem device  714  and the gateway  712 , the media server  710  may send a notification back to the gateway which may in turn notify the wireless handheld telephony device  11  that a path is available. 
     In further embodiments, a path may be established between the modem device  714  and the gateway  712  by creating a temporary call leg between the modem device  714  and the gateway  712  and temporarily suspending or holding the call leg from the gateway  712  to the second telephony device  750 . In such embodiments, a path may not be available at  904  and may need to be established at  906 . Where the message originates from the wireless handheld telephony device  11 , the wireless handheld telephony device  11  may send a signal to the media server  710  through the gateway  712  to establish the third call leg. The signal may, for example, be in the form of a tone such as a DTMF tone. Once the third call leg is established to the modem device  714  and the second call leg to the second telephony device  750  is temporarily suspended, the gateway  712  may send a notification back to the wireless handheld telephony device  11  that the path is available. 
     At  910 , the message data may be modulated and/or encoded into signals which may be transmitted via an audio stream by a modem device  128  associated with the wireless handheld telephony device  11 . 
     At  912 , the modulated/encoded signals may be sent to the gateway  712  through the first call leg between the gateway  712  and the wireless handheld telephony device  11 . At  914 , the modulated/encoded signals may be sent to the modem device  714 . The data may be decoded (if necessary) by codec  708  and demodulated by the demodulator  718 . At  916 , the data message may be received by the call control server  704 . 
     In some embodiments, a path between the modem device  714  and the gateway  712  may need to be closed or disabled, at  918 , once signals have been sent to the modem device  714 . For example, where a temporary conference bridge has been established in order to facilitate the transmittance, this conference bridge may be disabled by, for example, the media server  710 . In other embodiments, where a temporary call leg has been established to the modem device  714 , as explained above, the temporary call leg may be disabled and the second call leg to the second telephony device  750  may be re-established or unsuspended at  918 . 
     While the steps of methods  800  and  900  are shown as occurring in a particular order, it will be appreciated by those skilled in the relevant arts that many of the process steps, and portions thereof, are interchangeable and may occur in different orders that that shown without materially affecting the end results of the methods  800  and  900 . It will further be appreciated by such persons that not all of such steps are required in order to accomplish the purposes disclosed herein, and that further steps may be optionally implemented. 
     While the disclosure has been provided in connection with specific, presently-preferred embodiments, many variations and modifications may be made without departing from the spirit and scope of the invention. The disclosure is therefore not to be limited to the exact components or details of methodology or construction set forth above. Except to the extent necessary or inherent in the processes themselves, no particular order to steps or stages of methods or processes described in this disclosure, including the Figures, is intended or implied. In many cases the order of process steps may be varied without changing the purpose, effect, or import of the methods described. The scope of the claims is to be defined solely by the appended claims, giving due consideration to the doctrine of equivalents and related doctrines.