Abstract:
The present disclosure is directed to a system and method configured to implement an inter-MSC based handoff of a mobile device between a packet switched network and a mobile core network. In embodiments implementing a handoff from a femtocell to a macrocell, from the perspective of a neighboring MSC on a mobile core network, IP or VOIP information from a femtocell which is in communication with the convergence server, is perceived as having the same protocol as information which originates from a macrocell. Inversely, in embodiments implementing a hand-in to the femtocell from a macrocell, information which originates from a macrocell, which is in communication with the convergence server, would be perceived as IP or VOIP code to the femtocell. Accordingly, a target MSC in a handoff is agnostic of the fact that the mobile device entering into the macrocell was actually attached to a femtocell. Thus, embodiments of the present invention allow existing inter-MSC based handoff solutions to be leveraged.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Provisional U.S. Patent Application No. 61/201,836, filed on Dec. 15, 2008; this application is a continuation-of-part of U.S. patent application Ser. No. 12/172,238, filed on Jul. 13, 2008; U.S. patent application Ser. No. 12/172,238 claims benefit to Provisional U.S. Patent Application No. 60/949,846, filed Jul. 14, 2007; this application is a continuation-in-part of U.S. patent application Ser. No. 11/157,498, filed Jun. 21, 2005. 
    
    
     TECHNICAL FIELD 
     The following description relates generally to mobile device communication and, more particularly, to providing for effective handoff transitions of communications between wireless access points of packet switched networks and wireless access points of mobile core networks. 
     BACKGROUND OF THE INVENTION 
     Communication has become an ever increasing part of day-to-day life, both in business and personal lives. Accordingly, various forms of communication devices have become nearly ubiquitous. For example, a very large portion of the world&#39;s population have and utilize mobile devices, such as cellular telephones, personal communication system (PCS) phones, personal digital assistants (PDAs), smart phones, personal computers (PCs), etc., to provide voice and/or data communication. To provide highly mobile operation, such mobile devices often operate wirelessly to communicate with a host network. Thus, the mobile devices may be, for example, portable, pocket, hand-held, computer-included, or car-mounted devices which communicate voice and/or data wirelessly via a host radio network. Of course, such mobile devices can be fixed mobile devices, e.g., fixed cellular devices/terminals which are part of a wireless local loop or the like. 
     Cellular networks are well known for providing communications with respect to various mobile devices. In a typical cellular network, mobile devices communicate via a radio access network (RAN) to devices coupled to the cellular network. The RAN traditionally covers a geographical area which is divided into cell areas, with each cell area being served by a base station. The area coverage of such a base station, or cell area, is sometimes referred to as a macrocell. The base stations communicate over an air interface (e.g., radio frequencies) with the mobile devices or other mobile devices within range of the base stations. These base stations are typically positioned to bring the greatest coverage to the greatest number of cellular telephone users. 
     In the RAN, several base stations are typically connected (e.g., by landlines or microwave) to a radio network controller (RNC). The RNC, also sometimes termed a base station controller (BSC), supervises and coordinates various activities of the plural base stations connected thereto. The RNCs are typically connected to one or more systems (e.g., a mobile switching center (MSC)) providing the core communication services (e.g., call connect, call accounting, enhanced telephony services (ETSs) such as voice mail, one number service, call back service, language translation, call waiting, three-way calling, caller ID, do not disturb, and call forwarding service, public switched telephone network (PSTN) interfacing, etc.). 
     One example of a RAN is the universal mobile telecommunications (UMTS) terrestrial radio access network (UTRAN). The UMTS is a third generation system which in some respects builds upon the radio access technology known as global system for mobile (GSM) developed in Europe. UTRAN is essentially a RAN providing wideband code division multiple access (WCDMA) to mobile devices. Other types of cellular telecommunications systems which encompass RANs include, but are not limited to GSM systems, advance mobile phone service (AMPS) systems, narrowband AMPS (NAMPS) systems, total access communications system (TACS) systems, personal digital cellular (PDC) systems, United States digital cellular (USDC) systems, and code division multiple access (CDMA) systems (e.g., as described in EIA/TIA IS-95). 
     Cellular networks such as those described above are referred to herein as a “mobile core network” (or simply “mobile core”) and typically provide a circuit switched network. It should be appreciated that, although terms typically associated with particular network standards and protocols have been used in describing exemplary mobile core networks above, mobile core networks as discussed herein may comprise various configurations, such as GSM, CDMA, time division multiple access (TDMA), UMTS, second generation (2G), third generation (3G), high speed packet access (HSPA), time division-synchronous code division multiple access (TD-SCDMA), time division-code division multiple access (TD-CDMA), etc. The makeup and functionality of these and other mobile core networks is well-known in the art and is thus not described further herein. 
     It should be appreciated that, in a traditional cellular network, the coverage of the macrocell base stations is often not uniform. For example, individual buildings (e.g., homes, offices, etc.) may have weak signals indoors. Accordingly, more recently the addition of femtocell base stations (sometimes referred to as “home base stations,” “access point base stations,” “3G access points,” “small cellular base stations,” and “personal 2G-3G base stations”) has evolved. 
     In general, a femtocell base station is a small cellular base station designed for use in residential or small business environments. It connects to the service provider&#39;s network via a broadband packet switched network (such as using digital subscriber line (DSL), asymmetric digital subscriber line (ADSL), or cable internet) and typically supports 1 to 5 mobile devices (e.g., telephones) in a residential or business setting. In general, the femtocell incorporates the functionality of a typical base station but extends it to allow a simpler, self-contained deployment. 
     A femtocell base station allows service providers to extend service coverage within a targeted small geographic location, such as within a user&#39;s home or business—especially where access would otherwise be limited or unavailable—without the need for an expensive traditional cellular base station to be added to provide communication services for use by a small number of mobile devices. That is, although there may be hundreds or thousands of areas in which the mobile core network does not provide adequate coverage for communication services, each such area may have a very few mobile devices operated therein. Deploying a relatively small and inexpensive femtocell base station, leveraging a readily available broadband packet switched network such as the Internet to provide a communication link to the mobile core network, facilitates economic mobile device communications within these areas otherwise unserved or inadequately served by traditional macrocell base stations. 
     A femtocell base station may thus be deployed directly within a wireless subscriber&#39;s premises, such at a home or office. With a femtocell base station, the wireless communication device (e.g., cellular telephone) accesses the femtocell base station through traditional licensed spectrum. However, using such femtocell base stations, connectivity to the mobile core network is provided through the packet switched network using voice over internet protocol (VoIP) and/or internet protocol multimedia subsystem (IMS) technologies. 
     As can be appreciated from the foregoing, communication protocols and processing paths that are used in a network implementing a packet switched network (e.g. a femtocell), are different than those traditionally used for communication with the mobile core network. As a result, difficulties arise when a mobile device attempts to hand-in or hand-out between a femtocell and a macrocell. 
     Current solutions deployed in the market to address hand-in/hand-out difficulties do not support a hand-in to the femtocell network from a macrocell network, or a hand-out of the femtocell network to a macrocell network, while a mobile device is on an active call. As a result, an ongoing active call will be dropped either when a user is coming into the femtocell or leaving the femtocell. 
     One proposed solution to enable hand-in and hand-out of a mobile device during an active call is a voice call continuity (VCC) based approach. VCC approaches require mobile devices to be able to support concurrent calls on a mobile core network and on a packet switched network. Because the VCC based approach forces the mobile device to use its resources to support a redundant connection on two networks, needless overhead is created and devices must possess additional functionality to enable them to communicate on both networks simultaneously. In other words, mobile devices implementing a VCC approach can not be legacy devices (e.g. mobile devices adapted for mobile core network communications without specific adaptation for such communications to be provided via a packet switched network). Another limitation of the VCC solution is that in order to seamlessly hand off a call, the call must always be routed through a VCC server due to the inability to predict when a mobile device will enter or exit a femtocell or macrocell. As a result, even on a call that is between devices that are transmitting solely on a mobile core network, the call must be routed through the VCC server, thereby inserting inefficiency. 
     Another issue that results from differing protocols used in networks implementing a femtocell and those traditionally used for communication with a mobile core network is apparent when attempting to identify users within the different networks. In a packet switched network, or especially in an IMS network, users are often identified using a session initiation protocol (SIP) identifier or other identifier, which is similar to an email address (e.g. user@IMS.Tatara.com). Whereas in a mobile core network, users are typically identified using an MDN, which is a 10-digit mobile number. A packet switched network is not aware of the MDN and a mobile core network is not aware of the packet switched network public user identity. This introduces a problem because a user gets registered in the packet switched domain using the public user identity, whereas the real identity of that macro user is the MDN. So moving forward, if the carrier wants to handoff of the packet switched network&#39;s services, then it would need to know the MDN of the user. 
     Currently, if the MDN of the user is not known, in order to allow handoff of the packet switched network&#39;s services, the information must be downloaded from a visitor location register (VLR). So there is a disconnect between the databases of the differing networks. Another problem is if a user that is subscribed to an access point in a packet switched network (e.g. a femtocell) has moved onto another service provider network, for example from Sprint to Verizon, then the subscriber would need to be deleted from two separate databases, the home location register (HLR) database, and the home subscriber server (HSS) database. Therefore, currently there are two databases that need to be maintained for a femtocell subscriber being served. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is directed to a system and method configured to implement an inter-MSC based handoff of a mobile device between a packet switched network and a mobile core network. In embodiments implementing a handoff from a packet switched network to a mobile core, from the perspective of a neighboring MSC on a mobile core network, information received from the packet switched network is perceived as having the same protocol as information which originates from the mobile core network. Inversely, in embodiments implementing a hand-in to the packet switched network from the mobile core network, information which originates from a mobile core network would be perceived having the same protocol as information in a packet switched network. Accordingly, a target MSC in a handoff is agnostic of the fact that the mobile device entering into the mobile core network was actually attached to a packet switched network. Thus, embodiments of the present invention allow existing inter-MSC based handoff solutions to be leveraged as opposed to a VCC method of doing a handoff. 
     Additionally, embodiments are configured to execute a handoff is without requiring the mobile device to simultaneously broadcast using two protocols. Further, embodiments provide for a seamless handoff between networks, even during active voice calls. 
     Some embodiments implement an inter-MSC based handoff of a mobile device between a packet switched network and a mobile core network by utilizing a convergence server. Such a convergence server is configured to communicate with, and gather information from, devices in the mobile core network. Using this information and communication abilities, the convergence server is able to communicate with the mobile core network in a manner which makes the convergence server appear to be an MSC. Hence, known inter-MSC based handoff techniques are able to be implemented between the mobile core network and the packet switched network. 
     Embodiments are also configured to manipulate communication trunks. For example, once a phone is handed off to the mobile core network, the communication path that was established with a femtocell will be diverted to the target MSC. Since aspects of the packet switched network may not have a dedicated media gateway server, embodiments of the present invention provide for a system, such as a convergence server, that is configured to manipulate a media server that is already in the path of the call. Using an existing media server to do the handoff and have the traffic diverted to the target MSC reduces the cost of the overall solution because the it allows the system to leverage existing media servers. 
     Embodiments may also function to assist in the identification and registration users entering areas which utilize different protocols. For example, a convergence server may be utilized identify new users and to notify relevant databases of the identifiers of a new user which are used separate networks. In this manner, networks that handle users that have multiple identifiers, for example an MDN and an SIP identity, are able to more efficiently hand off such users. 
     The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which: 
         FIG. 1  shows a communication system adapted according to embodiments of the invention; 
         FIG. 2  shows a high level flow diagram of a hand-out routine according to embodiments of the invention; 
         FIG. 3  shows a high level flow diagram of a hand-in routine according to embodiments of the invention; and 
         FIGS. 4A ,  4 B,  5 A and  5 B show changes in communication paths as a result of handoff events according to embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows communication system  100  adapted according to an embodiment of the invention. Communication system  100  of the illustrated embodiment includes femtocell base station  110  coupled mobile core network  130  via packet switched network  120 . Communication system  100  is operable to provide for an inter-MSC based handoff between a macrocell and a femtocell for communication devices, such as mobile devices  101  and  102  which are on an active call and have need to hand-in/hand-out of the respective networks. As will be appreciated from the description of embodiments below, facilitating hand-in or a hand-out according to embodiments may be accomplished without modification to the legacy communication devices or mobile core network  130 . 
     Mobile devices  101  and  102  of the illustrated embodiment may comprise various configurations of communication devices. For example, mobile devices  101  and  102  may comprise cellular telephones, personal communication system (PCS) phones, personal digital assistants (PDAs) (e.g., the BLACKBERRY device available from Research In Motion), smart phones, personal computers (PCs), etc., operable to provide voice and/or data communication. Mobile devices  101  and  102  are referenced herein as legacy communication devices in order to describe concepts of the present invention. It should be appreciated, however, that communication system  100 , including femtocell base station  110 , may accommodate both legacy communication devices and non-legacy communication devices (e.g., communication devices which convert cellular signals to SIP and interfaces to a SIP-MSC inter-working function (IWF) which connects to the SIP (or IMS) network as well as the circuit-switched network). 
     Mobile core network  130  is adapted to provide communication services (e.g., cellular telephony service, short message service (SMS), general packet radio service (GPRS), multimedia broadcast service, etc.) to various communication devices, such as mobile devices  101  and  102 . Specifically, mobile core network  130  of the illustrated embodiment includes systems, data, and interconnections providing a radio access network (RAN) for providing communication services to various communication devices. Accordingly, mobile core network  130  is shown to include base station  132  for communicating over an air interface (e.g., radio frequencies) with the mobile devices or other mobile devices within range (within the macrocell area) of the base station. Mobile core network  130  is additionally shown to include home location register (HLR)  131 , such as may comprise a database of information (e.g., international mobile subscriber identity (IMSI), mobile subscriber integrated services digital network number (MSISDN), services enabled for the mobile device, settings to allow the mobile device to access packet services, visitor location register (VLR), serving GPRS support node (SGSN), enhanced telephony services (ETSs) settings, etc.) for each mobile device that is authorized to use mobile core network  130 . 
     Mobile core network  130  may comprise additional or alternative systems, data, and interconnections. For example, embodiments of mobile core network  130  will typically comprise a large number of base stations connected (e.g., by landlines or microwave) to radio network controllers (RNCs) or base station controllers (BSCs)  133 . Additionally, mobile core network  130  may comprise a mobile switching center (MSC)  134  communatively coupled to the RNCs/BSCs  133  and providing the core communication services. Mobile core network  130  of embodiments will typically be coupled to the public switched telephone network (PSTN) (not shown) so as to facilitate communications between mobile devices and devices coupled to the PSTN, including mobile devices of other mobile core networks also coupled to the PSTN. 
     General operation of a mobile core network, such as mobile core network  130 , in providing communication services to a plurality of communication devices is well known and will not be discussed in detail herein. It should be appreciated, however, that the coverage areas provided by base stations (e.g., base station  132 ) of mobile core network  130  may not provide adequate coverage of all areas in which users wish to operate mobile devices for communication services. For example, coverage gaps, coverage shadows, etc. may exist in various areas, such as within a building, on the far side of a mountain or other terrain, etc. Likewise, coverage may not be provided in certain areas, such as in rural areas, beyond the physical service limits of the service provider, etc. Accordingly, femtocell base stations, such as femtocell base station  110 , is utilized to provide communication services within areas otherwise not serviced or inadequately serviced by mobile core network  130 . 
     Femtocell base station  110  of the illustrated embodiment comprises a small base station providing operation mimicking or emulating that of a base station, such as base station  132 , of mobile core network  130 . That is, femtocell base station  110  provides an air interface to mobile devices, such as mobile device  101 , which functions the same as the air interface provided by a typical base station of mobile core network  130  (e.g., utilizes frequencies, channels, protocols, etc. native to the mobile core network), albeit at perhaps lower transmission power due to the typically smaller size of the femtocell coverage area. For example, femtocell base station  110  may comprise a universal mobile telecommunications (UMTS) configured base station containing a Node B, RNC and general packet radio service support node (GSN) with Ethernet for backhaul through packet switched network  120 . Additionally or alternatively, femtocell base station  110  may comprise a configuration compatable with other communications solutions, such as GSM, CDMA2000, TD-SCDMA, and/or WiMAX. 
     The illustrated embodiment of femtocell base station  110  connects to mobile core network  130  via packet switched network  120 . For example, femtocell base station  110  may utilize a digital subscriber line (DSL), asymmetric digital subscriber line (ADSL), or cable internet connection available at its deployment location to connect to packet switched network  120 . Connectivity to mobile core network  130  may be provided through packet switched network  120  using such technologies as voice over internet protocol (VoIP), internet protocol multimedia subsystem (IMS), etc. Accordingly, femtocell base station  110  of embodiments may utilize various architectures, such as a SIP/IMS, based architecture or an IP RAN based architecture. 
     Packet switched network  120  of the illustrated embodiment comprises a broadband packet switched network providing information communication supporting digitized data exchange suitable for communication links between mobile devices, such as mobile device  101 , and other devices, such as mobile device  102 , devices coupled to the PSTN (not shown), devices coupled to packet switched network  120 , etc. Accordingly, packet switched network  120  of the illustrated embodiment comprises packet data gateway/packet data information function (PDG/PDIF)  121 , authentication, authorization, and accounting (AAA) server  122 , convergence server  123 , and media server  124  operable to facilitate communications according to embodiments of the invention. 
     PDG/PDIF  121  of embodiments provides a packet switched network data gateway facilitating data packet communication between devices, such as femtocell base station  110 , and other devices of packet switched network  120 . For example, PDG/PDIF  121  may provide interfacing, link security, protocol conversion, data packet routing, and/or other functions for network edge devices, such as femtocell base station  110 . 
     AAA server  122  of embodiments provides centralized access, authorization and accounting management for devices to connect and use a network service of packet switched network  120 . For example, AAA server  122  may implement internet protocol secuirty (Ipsec) protocols for establishing mutual authentication, negotiation of cryptographic keys to be used during a communication session, etc. 
     Media server  124  of embodiments provides media content arbitration between mobile core network  130  and devices coupled to packet switched network  120 . For example, media server  124  may facilitate voice, video, and/or other media links between mobile core network  130  and mobile device  101  by accommodating the different protocols of mobile core network  130  and packet switched network  120 . 
     Convergence server  123  of embodiments of the present invention provides interfacing between packet switched network  120  and mobile core network  130  which facilitates in providing the communication services of mobile core network  130  to mobile devices, such as mobile device  101 , coupled to mobile core network  130  via packet switched network  120 . For example, convergence server  123  of embodiments facilitates the hand-in/hand-out of legacy mobile devices on active calls which have need of transitioning between femtocell  110  and a macrocell supported by base station  132 . Convergence server  123  of embodiments may provide control with respect to various systems and devices, such as femtocell base station  110 , PDG/PDIF  121 , AAA sever  122 , media server  124 , etc., to provide operation as described herein. 
     Convergence server  123  of embodiments further operates to provide functionality of a MSC for base stations (e.g., femtocell base station  110 ) coupled through packet switched network  120 . Accordingly, convergence server  123  interacts with mobile core network  130 , and other communication core networks (e.g., other mobile core networks, the PSTN, etc.), as a MSC to facilitate call setup, and other communications consistent with the communication protocols of such communications networks. Additionally, because convergence server  123  contains the functionality of an MSC, mobile devices  101  and  102  are able to seamlessly be handed between the protocols of core network  130  and packet switched network  120 . This is also done without dropping the respective active calls, and without requiring mobile devices  101  and  102  to broadcast simultaneous calls on core network  130  and packet switched network  120 . 
     Embodiments may also function to identify and register users entering areas which utilize different protocols. When a user, such as mobile device  101  is registered in the packet switched network, a third party registration is initiated to convergence server  123  which notifies convergence server  123  of the public user identity of that mobile device  101  that has been assigned on the packet switched network. A user registration is also implemented on HLR  131  using information from mobile device  101 . Upon a successful registration and authentication in the HLR  131 , the MDN of mobile device  101 , which may be a 10-digit mobile identity number on the mobile core network  130 , is downloaded to convergence server  123 . At this point in time, convergence server  123  can notify a HSS (not shown), or AAA  122 , of the association between the public user identity on the packet switched network, and the MDN identity of the subscriber. Convergence server  123  may also create a database association of the two different identities so that if future packet switched network services need to be provided to the mobile device when it is on the mobile core network, the packet switched network access the HSS and retrieve any information required for services, as opposed requesting that the convergence server get the information. 
       FIG. 2  shows a high level flow diagram  200  of an exemplary hand-out routine wherein a mobile device is connected on an active call on a packet switched network, and is attempting to transition to a mobile core network. When mobile device  101  starts moving away from a packet switched network&#39;s access point, such as femtocell  110 , mobile device  101  recognizes that a handoff is desired because, for example, the signal strength for a different base station is higher than that of femtocell  110 , and therefore it initiates a handoff request to the femtocell  110 . Femtocell  110  encapsulates information from the request and sends it to source MSC  201 , in handoff request message  202 . It is noted that in some embodiments, source MSC  201  may be implemented by convergence server  123 . Source MSC  201  sends a request to media server  124  for to assign a new circuit ID  203 . Since a convergence server, or source MSC  201 , may not have a dedicated media gateway, embodiments may use media server  124  to establish a communication path. The circuit ID contains routing information corresponding to the communication path (e.g. the current availability of the path) which will be established after the handoff is complete. Media gateway server  124  responds to request  203  and notifies source MSC  201  of the new circuit ID  204 . It is noted that request  203  and notification  204  may be implemented by using a SIP request. SIP protocol may be advantageous because it alleviates the need to implement other established media gateway control protocols. 
     Convergence server, or source MSC  201  may then take the new circuit ID information and use inter-MSC based messaging techniques to send routing information  205  (e.g. circuit ID information) for the device to target MSC  134 . Target MSC  134  then sends a handoff request  206  to the target RNC  133  which obtains an and information from the base station  132  ( FIG. 1 ) regarding its capacity and availability. Assuming that base station  132  is ready to support mobile device  101 , target RNC  133  sends back an acknowledgement message  207  to target MSC  134 , indicating that the mobile core network is prepared to provide access to mobile device  101 . Target MSC  134  then relays this acknowledgement and any other routing information  208  (such as the availability information of base station  132 ) that source MSC  201  may desire. 
     At this point the source MSC  201  sends a handoff command  209  to femtocell  110 , and femtocell  110  responds and notifies source MSC  201  that the handout has commenced  210 . The mobile core network then sets up dummy traffic channel  211 . Once dummy traffic channel  211  is established, then RNC  133  is able to send the handoff complete message  212  to target MSC  134 . Target MSC  134  will then send a final message to source MSC  201  to indicate that the target MSC is ready for the handoff  213 . In response, source MSC  202  sends an update message  214  to the media server  124  and informs media server  124  to bind the circuit ID that was provided initially. The circuit ID that was originally given by media server  124  is then bound and a message  215  reflecting such is conveyed to media server  124  from source MSC  201 . Once those two contacts happen the source MSC sends a clear command  216  to femtocell  110  which causes femtocell  110  to terminate its communication path with mobile device  101 . 
     As stated above, methods, such as the one shown above, which use a convergence server to work as an MSC in order to hand off active calls to a target MSC offer significant advantages over present femto/macrocell communication systems, including elimination of redundancy, simplification of mobile devices, and better performance with active mobile device calls. The convergence sever is able to function as an MSC as a result of the communication abilities shown herein (e.g. using SIP to send the commands down to the media gateway server, and to communicate with the femtocell). It is noted that other communication protocols may be used with the convergence server such as H248. However, at the present time SIP appears to be the simplest way to communicate between the convergence server and the media server. 
       FIG. 3  shows a high level flow diagram  300  of a hand-in routine wherein a mobile device  102  is connected on an active call on a mobile core network, such as mobile core network  130 , and is attempting to transition to a packet switched network, such as packet switched network  120 . In this case, RNC  133  would initiate a handoff required message  302  to the MSC that is serving mobile device  102 , e.g. MSC  134 , which for this embodiment is the source MSC. Source MSC  134  sends to MSC  301  (which is now the target MSC), a directed message  303  containing routing information including information about mobile device  102 . Target MSC  301  in this embodiment may also be implemented by convergence server  123 . Target MSC  301  initiates a handoff request message  304  to the packet switched network&#39;s access point, shown as femtocell  110 . The handoff request is then acknowledged  305  by femtocell  110 . 
     Since femtocell  110  is a known device on the packet switched network, i.e. it is registered, handoff request message  304  will go through an packet switched network. But since the mobile device  102  is not registered in the packet switched network, when subsequent messages are sent over the packet switched network, mobile device  102  will not receive the messages. Thus, it is preferable to register mobile device  102  on the packet switched network. One method of registering mobile device  102  is implemented by the having the access point, such as femtocell  110 , send message  305  to register, via packet switched network  120 , mobile device  102  based on the information provided about the mobile device in handoff request  304 . Message  305  may be sent, for example, by using SIP or any other protocol compatible with the network devices. This registration method will result in having subsequent messages sent to mobile device  102  sent to femtocell  110 , which can then be relayed to mobile device  102 . Registration methods, such as the ones described herein are also set forth in concurrently filed application referenced above entitled “Security for Legacy Communication Devices when Operating on Packet Switched Networks.” 
     It is noted that there are other methods to register the mobile device. The example set forth above utilized femtocells which undertook the registration on behalf of the handset, even though the handset is not fully moved into the femtocell. Another exemplary method for registering the mobile device entails using the convergence server can finish the registration directly using the HSS interface, and the information coming into the IMS code. 
     At this point the circuit ID is known, and an invite is sent with that circuit ID information  307  to media server  124 . Media server  124  is notified that this circuit ID needs to be tied to a call to be routed to femtocell  110 , and media server  124  acknowledges such in response message  308 . Routing information  309  is then sent from target MSC  301  to source MSC  134 . 
     At this point, a handoff command  312  may be sent to RNC  133  and RNC  133  responds with a handoff commenced message  310 . Once the handoff commenced message  311  is sent, a dummy path  312  is established. Finally, the femtocell sends a handoff complete message  313  and that will trigger the target MSC  301  to send an update  316  to the previous circuit ID information  307  message that was previously sent to media server  124  to notify media server  124  that the call will be routed through target MSC  304 . And a response  315  is sent to the source MSC once the update  314  is complete. At this point an on channel signal  316  is sent to source MSC  303 , and source MSC  303  will send a clear command  317  to RNC  133 , which will release the traffic channel for mobile device  300  that just entered into femtocell  307 . 
       FIGS. 4A and 4B  illustrate the movement of a data path  401  and control path  402  which occurs as a result of a handout of a femtocell to a mobile core, such as is illustrated in  FIG. 2 . In  FIG. 4A  mobile device  403  is in communication with femtocell access point  404  and PDG/PDIF  405  when mobile device  403  is communicating on a packet switched network. The data path  401  is routed through media server  406  and MGCF  410 , and then to a destination, such as PTSN  407 . The control path is sent through call session control function circuitry (CSCF)  408 , and then to the convergence server  409 . Convergence server  409  routes control path  402  back through CSCF  408  and then to MGCF  410  for. After the MGCF, data signal  402  is sent to PTSN  407 . 
     Embodiments are also configured to manipulate communication trunks. For example, as shown in  FIGS. 4A and 4B , once mobile device  403  is handed off to the mobile core network  411 , data path  401  that is going through the femtocell  412  will be diverted to target MSC  413 . Data path  401  will also pass through base station  414  and connects with mobile device  403 . Control path  402  will also span between MSC  413  and convergence server  409 . It is also noted that signaling system protocols, such as signaling system number 7 (SS7), may control various aspects of the illustrated communications paths, such as the control path between MSC  413  and convergence server  409 . 
     Since convergence server  409  does not have a dedicated media server, embodiments of the present invention provide for a convergence server that is configured to manipulate media server  406  which is already in the path of the call. For example, embodiments of the present invention provide for a convergence server that is configured to utilize media server which is part of a VOIP, IMS network, etc., to have the traffic from the mobile core network directed towards the media server, and the media server can direct the flow of traffic to the target MSC. Sharing an existing media server to do the handoff and have the traffic diverted to the target MSC reduces the cost of the overall solution because the it allows the system to leverage existing media servers. 
     Likewise,  FIGS. 5A and 5B  show mobile device  500  which is being handed-in from macrocell  501  to femtocell  502 , such as is illustrated in  FIG. 3 . When mobile device  502  is communicating on macrocell  501  the data path  503  and control path  504  are both directed through BSS  505  and MSC  506  to their destination, such as PTSN  507 . When a handoff request is communicated, the control path  504  is diverted from MSC  506  to connect to convergence server  509 , which is also in communication with MGCF  507  and CSCF  508 . Embodiments of the present invention cause convergence server  509  to appear to MSC  506  as being another MSC, and in this case the target MSC. Convergence server  509  causes MSC  506  to divert the data path  503  to media server  510  and it is then routed through PDG  511  and femtocell access point  512  and then to mobile device  500 . Control path  504  is also routed through PDG  511  and femtocell access point  512  and then to mobile device  500 . As can be seen by this illustration, after the hand-in is complete, the communication path through the MSC  506  is still utilized and in the femtocell communication paths. Additionally, as with the example of  FIGS. 4A and 4B , signaling system protocols, such as SS7, may control various aspects of the illustrated communications paths, such as the control path between MSC  506  and convergence server  509 . 
     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.