Abstract:
Systems and methods are provided herein for transferring an active voice call to a packet communication network. In a particular embodiment, a method provides establishing a voice call having an initial signaling channel and an initial voice channel between a first wireless device and a second wireless device over a first and second wireless access system. The method further includes establishing a new signaling channel for the voice call between the first wireless device and a separate packet network. Also, the method provides extending the new signaling channel for the voice call from the separate packet network to the second wireless access system over the first wireless access system. Furthermore, the method includes using the new signaling channel to establish a new voice channel for the voice call over the separate packet network, wherein the first wireless access system remains in the new signaling channel.

Description:
TECHNICAL BACKGROUND 
     Wireless communication devices communicate with other devices and systems by connecting to wireless communication systems. Typically a wireless device will use a cellular voice protocol, such as 1x Code Division Multiple Access (CDMA) or the Global System for Mobile communications (GSM). Wireless devices communicating using these protocols are able to transfer between access node without losing connectivity for an in progress call. This transfer process is commonly referred to as handing off between access nodes. 
     Newer wireless protocols, sometimes referred to as third or fourth generation wireless protocols, are more packet centric wireless protocols. Voice calls with a wireless device over a third or fourth generation protocol may use a packet based protocol, such as Voice over Internet Protocol (VoIP). Transferring an in progress call from a non-packet based connection to a packet based connection may be difficult. The transfer difficulties may cause the call to be dropped due to the difference in access protocols. 
     OVERVIEW 
     Systems and methods are provided herein for transferring an active voice call to a packet communication network. In a particular embodiment, a method provides establishing a voice call having an initial signaling channel and an initial voice channel between a first wireless device and a second wireless device over a first wireless access system and a second wireless access system. The method further includes establishing a new signaling channel for the voice call between the first wireless device and a separate packet network. Also, the method provides extending the new signaling channel for the voice call from the separate packet network to the second wireless access system over the first wireless access system. Furthermore, the method includes using the new signaling channel to establish a new voice channel for the voice call between the first wireless device and the second wireless access system over the separate packet network and to remove the initial voice channel for the voice call between the first wireless device and the second wireless access system over the first wireless access system, wherein the first wireless access system remains in the new signaling channel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a wireless communication system. 
         FIG. 2  illustrates the operation of a wireless communication system. 
         FIG. 3  illustrates a wireless communication system. 
         FIG. 4  illustrates the operation of a wireless communication system. 
         FIG. 5  illustrates a wireless access system. 
         FIG. 6  illustrates a communication control system. 
     
    
    
     DETAILED DESCRIPTION 
     The following description and associated figures teach the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects of the best mode may be simplified or omitted. The following claims specify the scope of the invention. Note that some aspects of the best mode may not fall within the scope of the invention as specified by the claims. Thus, those skilled in the art will appreciate variations from the best mode that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents. 
       FIG. 1  illustrates communication system  100 . Communication system  100  includes wireless communication device  101 , wireless communication device  102 , wireless access system  103 , wireless access system  104 , communication control system  105 , and packet network  106 . Wireless communication device  101  and wireless access system  103  communicate over wireless link  111 . Wireless communication device  102  and wireless access system  104  communicate over wireless link  112 . Wireless communication device  101  and packet communication network  106  communicate over wireless link  113 . Wireless access system  103  and wireless access system  104  communicate over communication link  114 . Wireless access system  104  and communication control system  105  communicate over communication link  116 . Wireless access system  103  and communication control system  105  communicate over communication link  115 . Packet communication network  106  and control system  105  communicate over communication link  117 . Packet communication network  106  and wireless access system  104  communicate over communication link  118 . 
     Wireless devices  101  and  102  may communicate with access systems  103  and  104 , respectively, via wireless access nodes, such as cellular base stations Likewise, wireless device  101  may communicate with packet network  106  via a wireless access node. The wireless access node used to communicate with packet network  106  may be the same or different from the access node used to communicate with access system  103 . 
     In operation, wireless device  101  is capable of communicating using various wireless communication protocols. Wireless device  101  communicates with access system  103  using a cellular voice protocol such as 1x Code Division Multiple Access (CDMA). Additionally, wireless device  101  communicates with packet network  106  using a packet cellular protocol, such as the fourth generation cellular protocol Long Term Evolution (LTE), to exchange voice communications over the packet network. The voice communications over packet network  106  may be Voice over Internet Protocol (VoIP) communications or some other packet based voice protocol. 
     The multiple voice formats and wireless protocols make switching between the two protocols difficult while wireless device  101  is participating in a voice call. For example, a call may be dropped when wireless device  101  transfers from access system  103  to packet network  106 . 
       FIG. 2  illustrates the operation of wireless communication system  100 . Access system  103  establishes a voice call having an initial signaling channel and an initial voice channel between wireless device  101  and wireless device  102  over access system  103  and access system  104  (step  200 ). The voice call may be initiated by either wireless device  101  or wireless device  102 . The initial signaling and voice channels may be the voice and signaling channels associated with a cellular voice protocol, such as 1x CDMA or the Global System for Mobile Communications (GSM). In particular, wireless links  111  and  112  may use 1x CDMA while link  114  may use packet based communications to communicate between access system  103  and access system  104 . Although, each link may use alternative communication formats. 
     Wireless device  101  then transfers from communicating with a cellular voice protocols over link  111  to communicating with a packet based communication protocol, such as LTE or WiMax, over wireless link  113 . This process may include transferring from communicating with an access node for wireless link  111  to communicating with an access node for wireless link  113  and is sometimes referred to as handing off. Wireless link  113  allows wireless device  101  to communicate with packet network  106 . Wireless device  101  may physically move in order to achieve the wireless signal connectivity necessary establish wireless link  113 , as indicated by the dotted arrow of  FIG. 1 , or wireless device  101  may have stayed in the same location and switched network access links. 
     Upon gaining communications with packet network  106 , wireless device  101  may notify communication control system  105  that wireless device  101  is now communicating over packet network  106  rather than access system  103 . Communication control system  105  establishes a new signaling channel for the voice call between wireless device  101  and packet network  106  (step  202 ). The new signaling channel may be a session initiation protocol (SIP) signaling channel. Packet network  106  is separate from access systems  103  and  104 . 
     Additionally, communication control system  105  extends the new signaling channel for the voice call from packet network  106  to access system  104  over access system  103  (step  204 ). The new signaling channel may span links  114 ,  115 ,  116 , control system  105 , and link  117  to packet network  103  or may take other paths and include other intermediate systems. 
     Communication control system  105  then uses the new signaling channel to establish a new voice channel for the voice call between wireless device  101  and access system  104  over packet network  106  (step  206 ). Also, communication control system  105  removes the initial voice channel for the voice call between wireless device  101  and access system  104  over access system  103 . Access system  103  remains in the new signaling channel. 
     Therefore, the process of  FIG. 2  begins with wireless device  101  participating in a cellular voice call with wireless device  102  via access system  103  and access system  104 . Both voice and control signaling pass through access systems  103  and  104 . The process ends with the same voice call having voice data now routed through packet network  106  to and from access system  104  while call signaling routes through packet network  106  through control system  105  and access system  103  to access system  104 . Thus, access system  103  still participates in the control signaling for the voice call even though the voice data no longer routes through access system  103 . 
     Referring back to  FIG. 1 , wireless communication devices  101  and  102  comprise Radio Frequency (RF) communication circuitry and an antenna. The RF communication circuitry typically includes an amplifier, filter, modulator, and signal processing circuitry. Wireless communication devices  101  and  102  may also include a user interface, memory device, software, processing circuitry, or some other communication components. Wireless communication devices  101  and  102  may be a telephone, computer, e-book, mobile Internet appliance, wireless network interface card, media player, game console, or some other wireless communication apparatus—including combinations thereof. 
     Wireless access systems  103  and  104  each comprise a computer system and communication interface. Wireless access systems  103  and  104  may also include other components such a router, server, data storage system, and power supply. Wireless access systems  103  and  104  each may reside in a single device or may be distributed across multiple devices. Wireless access systems  103  and  104  could each be an base station controller, Internet protocol base station controller, mobile switching center, network gateway system, Internet access node, application server, service node, or some other communication system—including combinations thereof. 
     Communication control system  105  comprises a computer system and communication interface. Communication control system  105  may also include other components such a router, server, data storage system, and power supply. Communication control system  105  may reside in a single device or may be distributed across multiple devices. Communication control system  105  may be an Internet protocol multimedia subsystem (IMS) platform, network gateway system, Internet access node, application server, service node, or some other communication system—including combinations thereof. 
     Packet communication network  106  is a communication network that comprises telephony switches, wireless access nodes, Internet routers, network gateways, computer systems, communication links, or some other type of communication equipment—including combinations thereof. 
     Wireless links  111 - 113  uses the air or space as the transport media. Wireless links  111 - 112  may use various protocols, such as Code Division Multiple Access (CDMA), Global System for Mobile Communication (GSM), or some other wireless communication format. Wireless link  113  may use various protocols for packet based wireless communications, such as Worldwide Interoperability for Microwave Access (WIMAX), Long Term Evolution (LTE), Wireless Fidelity (WIFI), or some other wireless communication format. Communication links  114 - 118  use metal, glass, air, space, or some other material as the transport media. Communication links  114 - 118  could use various communication protocols, such as Time Division Multiplex (TDM), Internet Protocol (IP), Ethernet, communication signaling, CDMA, EVDO, WIMAX, GSM, LTE, WIFI, HSPA, or some other communication format—including combinations thereof. Communication links  114 - 118  could be direct links or may include intermediate networks, systems, or devices. 
       FIG. 3  illustrates communication system  300 . Communication system  300  includes wireless communication device  301 , wireless communication device  302 , Internet protocol base station controller (IP BSC)  303 , IP BSC  304 , packet network  308 , and Internet protocol multimedia subsystem (IMS) platform  305  within packet network  308 , which includes home subscriber server (HSS)  306  and call state control function (CSCF)  307 . The arrows shown between elements of communication system  300  are abstract representations of various voice and signaling paths that will be described below. The dashed lines represent signaling paths for control communications while the solid lines represent voice paths for voice communications. Though links are not shown, the signal paths may use links similar to those described for communication system  100  of  FIG. 1 . 
       FIG. 4  illustrates the operation of communication system  300 . A voice call having an initial signaling channel and an initial voice channel is established between wireless device  301  and wireless device  302  (step  400 ). Voice paths  315  and  317  in the initial voice channel are 1x CDMA paths. The voice call is established through IP BSC  303  and IP BSC  304 . Voice path  316  between IP BSC  303  and IP BSC  304  uses Real-time Transfer Protocol (RTP). The voice call may have been initiated by either wireless device  301  or wireless device  302 . The initial signaling channel between wireless devices  301  and  302  and IP BSCs  303  and  304  are paths  311  and  312 , respectively. 
     At a point in time during the voice call, wireless device  301  transfers from the 1x CDMA connection that was initially used to connect with IP BSC  303  to an LTE connection. The dotted arrow in  FIG. 3  represents the move from CDMA to LTE, however, wireless device  301  may not need to move physically in order to achieve LTE connectivity. LTE is a packet based communication protocol that is considered to be a fourth generation wireless protocol. The LTE protocol provides that voice communications may be exchanged as packet communications with wireless communication device  301 . Thus, voice communications over LTE may operate in a manner similar to Voice over Internet Protocol (VoIP). 
     Upon moving to the LTE connection, wireless device  301  registers with IMS platform  305  through HSS  306  (step  402 ). IMS platform  305  provides or acts as an intermediary for packet based services, such as voice calls, for wireless devices. Registering with IMS platform  305  allows IMS platform  305  to recognize that wireless device  301  is now operating on packet network  308  over LTE. 
     In response to wireless device  301  registering connection, a new session initiation protocol (SIP) signaling channel for the call is established between wireless device  301  and packet network  308  that the LTE connection allows wireless device  301  to access (step  404 ). The SIP signaling channel follows paths  313  and  314  through CSCF  307  to exchange control signaling between wireless device  301  and IP BSCs  303  and  304 . 
     After the SIP signaling channel is created, wireless device  301  transfers a SIP update message to IP BSC  303  (step  406 ). The update message is transferred over path  313  in the SIP signaling channel. The update message indicates to IP BSC  303  that wireless device  301  is now operating on packet network  308 . The update message further includes a SIP address for wireless device  301 . IP BSC  303  transfers a SIP update message to IP BSC  304  indicating the SIP address for wireless device  301  (step  406 ). Once IP BSC  304  knows the SIP address for wireless device  301 , IP BSC  304  can route voice communications for the voice call to wireless device  301  over path  318 . Additionally, IP BSC  303  transfers a SIP update message to wireless device  301  indicating the SIP address of IP BSC  304  (step  406 ). Once wireless device  301  knows the SIP address for IP BSC  304 , wireless device  301  can route voice communications for the voice call to IP BSC  304  over path  318 . 
     After all SIP update messages have been transferred, the voice call that was initiated by wireless device  301  over 1x CDMA continues over LTE and packet network  308  (step  408 ). The signaling channel for control signals between wireless device  301  and IP BSC  304  continues through IP BSC  303  via paths  313 ,  314 , and CSCF  307 . The voice channel between wireless device  301  and IP BSC  304  does not go through IP BSC  303  but, instead, travels through packet network  308  on path  318 . Path  318  connects with the packet network via the LTE link from wireless device  301  and the RTP link from IP BSC  304 . During the above process, wireless device  302  continues to access IP BSC  304  using 1x CDMA path  317 . Any changes that occur regarding the transference of wireless device  301  to from 1x CDMA to LTE are transparent to wireless device  302 . Thus, the call between wireless device  301  and wireless device  302  continues uninterrupted by the switch to LTE by wireless device  301 . 
     Upon completion of the call, IP BSC  303  may be dropped from the signaling path. Thus, any subsequent calls to and from wireless device  301  while wireless device  301  is connected using LTE may not need signaling paths routed through IP BSC  303 . 
       FIG. 5  illustrates wireless access system  500 . Wireless access system  500  is an example of wireless access system  103 , although control system  103  may use alternative configurations. Wireless access system  500  comprises communication interface  501 , user interface  502 , and processing system  503 . Processing system  503  is linked to communication interface  501  and user interface  502 . Processing system  503  includes processing circuitry  505  and memory device  506  that stores operating software  507 . 
     Communication interface  501  comprises components that communicate over communication links, such as network cards, ports, RF transceivers, processing circuitry and software, or some other communication devices. Communication interface  501  may be configured to communicate over metallic, wireless, or optical links. Communication interface  501  may be configured to use TDM, IP, Ethernet, optical networking, wireless protocols, communication signaling, or some other communication format—including combinations thereof. 
     User interface  502  comprises components that interact with a user. User interface  502  may include a keyboard, display screen, mouse, touch pad, or some other user input/output apparatus. User interface  502  may be omitted in some examples. 
     Processing circuitry  505  comprises microprocessor and other circuitry that retrieves and executes operating software  507  from memory device  506 . Memory device  506  comprises a disk drive, flash drive, data storage circuitry, or some other memory apparatus. Operating software  507  comprises computer programs, firmware, or some other form of machine-readable processing instructions. Operating software  507  may include an operating system, utilities, drivers, network interfaces, applications, or some other type of software. When executed by circuitry  505 , operating software  507  directs processing system  503  to operate wireless access system  500  as described herein. 
     In particular, communication interface  501  establishes a voice call having an initial signaling channel and an initial voice channel between a first wireless device and a second wireless device over wireless access system  500  and a second wireless access system. 
       FIG. 6  illustrates communication control system  600 . Communication control system  600  is an example of communication control system  105 , although control system  105  may use alternative configurations. Communication control system  600  comprises communication interface  601 , user interface  602 , and processing system  603 . Processing system  603  is linked to communication interface  601  and user interface  602 . Processing system  603  includes processing circuitry  605  and memory device  606  that stores operating software  607 . 
     Communication interface  601  comprises components that communicate over communication links, such as network cards, ports, RF transceivers, processing circuitry and software, or some other communication devices. Communication interface  601  may be configured to communicate over metallic, wireless, or optical links. Communication interface  601  may be configured to use TDM, IP, Ethernet, optical networking, wireless protocols, communication signaling, or some other communication format—including combinations thereof. 
     User interface  602  comprises components that interact with a user. User interface  602  may include a keyboard, display screen, mouse, touch pad, or some other user input/output apparatus. User interface  602  may be omitted in some examples. 
     Processing circuitry  605  comprises microprocessor and other circuitry that retrieves and executes operating software  607  from memory device  606 . Memory device  606  comprises a disk drive, flash drive, data storage circuitry, or some other memory apparatus. Operating software  607  comprises computer programs, firmware, or some other form of machine-readable processing instructions. Operating software  607  may include an operating system, utilities, drivers, network interfaces, applications, or some other type of software. When executed by circuitry  605 , operating software  607  directs processing system  603  to operate communication control system  600  as described herein. 
     In particular, communication interface  601  establishes a new signaling channel for the voice call between the first wireless device and a separate packet network, and extends the new signaling channel for the voice call from the separate packet network to the second wireless access system over the first wireless access system. Communication interface  601  uses the new signaling channel to establish a new voice channel for the voice call between the first wireless device and the second wireless access system over the separate packet network and to remove the initial voice channel for the voice call between the first wireless device and the second wireless access system over the first wireless access system, wherein the first wireless access system remains in the new signaling channel. 
     The above description and associated figures teach the best mode of the invention. The following claims specify the scope of the invention. Note that some aspects of the best mode may not fall within the scope of the invention as specified by the claims. Those skilled in the art will appreciate that the features described above can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific embodiments described above, but only by the following claims and their equivalents.