Patent Publication Number: US-2021168474-A1

Title: Implementing intelligent network service functionality in a network

Description:
FIELD OF THE INVENTION 
     The present disclosure relates to telecommunications and, more particularly, to telecommunication systems including alternative mechanisms for implementing intelligent network trigger functionality. 
     BACKGROUND 
     The Intelligent Network (IN) comprises a network architecture that allows operators to provide value-added services in addition to the standard telecom services, e.g., Global System for Mobile Communications (GSM) services. IN infrastructure comprises an overlay of a core telecommunications network and provides enhancements to core telephony services. 
     An IN architecture includes, among other network entities, a Service Switching Function (SSF) or Service Switching Point (SSP). The SSF or SSP may be deployed with a switch or central office and functions as a trigger point at which IN services may be invoked during a call. The switch identifies Detection Points during a call or call setup and, responsive thereto, may invoke a query to a service control point (SCP) that contains service logic which implements the desired service. The query issued by the SSP to the SCP is typically referred to as a trigger. Trigger criteria are defined by the operator and may, for example, include the calling number or the dialed number. 
     Some carriers may only implement a subset of the triggering infrastructure and not all the triggers that an application requires. Moreover, when a subscriber is roaming, triggers may not be supported between the networks of different carriers. Thus, in many scenarios, IN services may be unavailable to a mobile terminal. 
     Heretofore, no mechanisms have been provided to support trigger functionality for IN based applications without involving the switching infrastructure. 
     SUMMARY OF THE INVENTION 
     Embodiments disclosed herein provide mechanisms for simulating IN triggers in a network system. A mobile terminal may be configured with an IN Simulator that is adapted to originate simulated IN triggers, for example in the form of USSD messages, SMS messages, or another suitable data structure. Call progressions implemented according to the simulated IN triggers may be managed or coordinated by at least one of a carrier-gateway server and an Enterprise-gateway server. Call progressions implemented by the simulated IN triggers may be specified according to Enterprise member policies or general Enterprise behaviors. In an embodiment, the IN Simulator is deployed on a mobile terminal SIM or on a mobile terminal capable of supporting a software client and is registered as a call observer function. The IN Simulator is adapted to generate simulated IN triggers for provisioning of IN service functionality in the network. The IN Simulator may generate messages related to call origination and termination events that facilitate provisioning of IN services without the network support of conventional IN triggers. Advantageously, if a carrier network does not support a trigger infrastructure that has capabilities of originating triggers and terminating triggers—or if a roaming agreement is not in place that allows the transfer of these triggers between carriers—the use of an IN Simulator provides an alternative mechanism that provides the information to a IN based application for providing IN service functionality without network support for IN triggers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures, in which: 
         FIG. 1  is a diagrammatic representation of a network system in which embodiments disclosed herein may be implemented for advantage; 
         FIG. 2  is a simplified block diagram of an exemplary mobile terminal in which embodiments may be implemented; 
         FIG. 3  is a diagrammatic representation of an exemplary software configuration of a mobile terminal adapted for originating simulated intelligent network triggers in accordance with an embodiment; 
         FIG. 4  is a diagrammatic representation of a signaling flow of a mobile originated call to an Enterprise member implemented in accordance with an embodiment; 
         FIG. 5  is a diagrammatic representation of a signaling flow of an Enterprise member placing a call to another Enterprise member from an enterprise landline telephony device implemented in accordance with an embodiment; 
         FIG. 6  is a diagrammatic representation of a signaling flow of a call originated from a PSTN device to an Enterprise member in accordance with an embodiment; 
         FIG. 7  is a diagrammatic representation of a signaling flow of a call originated from a PSTN device to an Enterprise member in accordance with an embodiment; 
         FIG. 8  is a diagrammatic representation of a signaling flow of a call originated from a PSTN device to an Enterprise member in accordance with an embodiment; and 
         FIG. 9  is a diagrammatic representation of a signaling flow of a call originated from an Enterprise member&#39;s mobile terminal to another Enterprise member implemented in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
       FIG. 1  is a diagrammatic representation of a network system  100  adapted to interconnect various networks and terminals deployed therein in which embodiments disclosed herein may be implemented for advantage. Carrier network  110  may comprise a code division multiple access (CDMA) carrier network, e.g., a CDMA2000-compliant network. Carrier network  110  may include any number of base transceiver stations (BTSs)  112   a - 112   c  communicatively coupled with a base station controller (BSC)  114 . Each individual BTS  112   a - 112   c  under the control of a given BSC may define a radio cell operating on a set of radio channels thereby providing service to a Mobile Terminal (MT)  125 . BSC  114  manages the allocation of radio channels, receives measurements from mobile terminals, controls handovers, as well as various other functions as is understood. BSC  1   14  is interconnected with a mobile services switching center (MSC)  116  that provides mobile terminal exchange services. BSC  114  may be additionally coupled with a packet data serving node (PDSN)  118  that provides a connection point between the CDMA radio access network and a packet network, such as Internet  140 , and provides mobility management functions and packet routing services. MSC  116  may communicatively interface with a circuit switched network, such as the public switched telephone network (PSTN)  130 , and may additionally be communicatively coupled with an interworking function (IWF)  122  that provides an interface between MSC  116  and Internet  140 . 
     GSM carrier network  150  includes gateway Mobile Switching Center (GMSC)  151  that provides an interface between PSTN  130  and carrier network  150 . GMSC  151  determines which MSC currently services a called mobile terminal. Carrier network  150  includes a Switching System (SS)  152  and a Base Station System (BSS)  156 . Each of SS  152  and BSS  156  contain a number of functional units well understood by those skilled in the art, and a detailed explanation of the various components is unnecessary. Nevertheless, a cursory review of various components is provided. SS  152  contains an MSC  153 , a Home Location Register (HLR)  154 , and a Visitor Location Register (VLR)  155 . MSCs carry out switching functions and manage the communications between mobile phones and the PSTN  130 . HLR  154  comprises the central database that contains details of each mobile phone subscriber that is authorized to use the cellular core network. VLR  155  comprises a database which stores information about all the mobiles terminals that are currently serviced by the associated MSC. VLR  155  stores various information regarding the mobile terminals, such as the current location area identity that specifies a particular BSC that the mobile station is currently serviced by. 
     Various other sub-systems or functional modules may, and typically are, included in SS  152 , such as an Authentication Center, an Equipment Identity Register, or various other functions. A serving general packet radio service (GPRS) support node (SGSN)  159  may be included in GSM carrier network  150  to facilitate provisioning of packet services to and from mobile terminals in network  150 . GPRS provides mobility management, session management and transport for Internet Protocol packet services in GSM cellular packet networks. 
     As is understood, various GPRS infrastructure may be included in network  150  to provide packet services to mobile terminals, and only SGSN  159  of the GPRS core network is depicted to simplify the discussion of embodiments disclosed herein. In general, a gateway GPRS support node may interface the GPRS backbone with an external packet network, such as the Internet. 
     SGSN  159  may interface with various subsystem of network  150 . For example, SGSN  159  may have a Gs interface with MSC  153  and VLR  155  that facilitates paging and station availability notification when performing data transfers. SGSN  159  may additionally have a Gr interface with HLR  154  through which messaging may be performed, for example, over the Mobile Application Part protocol. SGSN  159  may additionally have a Gb interface with packet control unit (PCU) (not shown) of BSS  156  that facilitates connection of BSS  156  with SGSN  159 . 
     Network  150  may also include a signaling system, such as a SS7 network  160 . SS7 network  160  provides a set of telephony signaling protocols which are used to set up the vast majority of the world&#39;s PSTN telephone calls. SS7 network  160  is also used in cellular networks, such as GSM and UMTS, for circuit switched voice and packet-switched data applications. As is understood, SS7 network  160  includes various signaling nodes, such as any number of service control points (SCPs)  162 , signal transfer points (STPs)  164 , and service switching points (SSPs)  166 . 
     BSS  156  contains a BSC  157  that may be in communication with and in control of a plurality of BTSs  158   a - 158   c . Each individual BTS  158   a - 158   c  under the control of a given BSC  157  may define a radio cell operating on a set of radio channels thereby providing service to an MT, e.g., MT  126 . 
     Network  150  may also include a short message service center (SMSC)  161  adapted to deliver short message service (SMS) messages to mobile terminals. When an SMS message is sent to a user, the SMS message is stored in SMSC  161  which delivers it to the destination mobile terminal when the destination mobile terminal is available. As is known, the SMS message may be delivered via a control channel, e.g., a cell broadcast control channel, or bearer channel. Network  150  may further include a Unstructured Supplementary Service Data (USSD) gateway  163  that provides real-time or instant messaging type phone services. USSD gateway  163  provides for transmission of information of GSM signaling channels. In accordance with embodiments disclosed herein, USSD services may be used in conjunction with an IN simulator deployed on a mobile terminal to provide for IN trigger service functionality as described more fully hereinbelow, although other messaging services, such as SMS, may be similarly utilized for implementing embodiments of the disclosure. 
     System  100  may include an enterprise network  170  that includes a PBX  171  that provides service to any number of extensions, e.g., enterprise terminal devices  172   a - 172   n . Additionally, PSTN  130  may interface with enterprise network  170 , e.g., by a tandem or other switch coupled with enterprise router  174 . Enterprise network  170  may include an enterprise gateway server (GS-E)  176  that may be communicatively coupled with a carrier gateway server (GS-C)  192  deployed in, or interconnected with, carrier network  150 . 
     The connection between GS-E  176  and GS-C  192  may be made over, for example, session initiation protocol (SIP) or other protocols. This configuration may enable carrier network  150  to have a central point of control for interacting with multiple enterprises, and may not require the use of SS7 messaging to the enterprise. Rather, it is possible to have a secure IP connection supporting SIP. This is also useful for offering a Centrex solution for interconnecting with a carrier-hosted PBX, or for interconnecting a carrier-hosted gateway server with enterprise-hosted PBX systems. GS-C  192  may support an SS7 point code multiplexer in which only one or two point codes are needed to address all enterprises since GS-C  192  can identify for which enterprise a message is intended. GS-E  176  may be adapted to provision GS-C  192  automatically over an IP interface to manage subscribers, e.g., to add new pilot directory numbers for new subscribers. In the illustrative example, respective users (illustratively designated “User 1” and “User 2”) are allocated a respective Enterprise terminal device  172   n  and  172   a  as well as a mobile terminal  125  and  126 . 
     From an IT organization perspective, GS-E  176  appears as an extension to PBX  171 . To carrier network  150 , GS-E  176  appears as a standard in-network endpoint for delivering calls. To PBX  171 , GS-E  176  appears as a set of standard PBX endpoints (e.g., deskphones, or IP clients). GS-E  176  mediates between the two disparate sets of network protocols and state machines. 
     GS-C  192  may include the network functions for both voice (gateway MSC) and data (gateway GPRS Support Node or Home Agent), VoIP capability for interconnecting carrier network  150  with Enterprise network  170  thereby eliminating PSTN interconnect charges, a billing gateway, and a next-generation Network Services gateway that enables third party value added services for the enterprise, such as mobile phone activation/de-activation, corporate directory integration based on IMS (IP Multimedia Subsystem), or other services. GS-C  192  may also include the element management subsystem (EMS) and a service management subsystem for the operational support system (OSS). 
     In the example depicted in  FIG. 1 , mobile terminals associated with Enterprise network  170  may be configured with an IN Simulator that is adapted to originate simulated IN triggers, e.g., in the form of USSD messages, SMS messages, SIP over GPRS or CDMA evolution-data optimized (EV-DO) or another suitable data structure. Call progressions implemented according to the simulated IN triggers may further be managed or coordinated by GS-C  192  and GS-E  176 , e.g., according to Enterprise member policies maintained by member database  178 . 
     PBX  171  may include or interface with an Enterprise member database  178  that stores records or profiles that define services for members of Enterprise network  170 . GS-E  176  may interface with member database  178  via a provisioning interface specific to PBX  171 . Enterprise member database  178  may include records that specify enterprise members and DID numbers of telephony devices allocated thereto. Additionally, enterprise member database  178  may specify usage policies for Enterprise members that may define, for example, allowable mobile terminal usage such as roaming capabilities, various preferred call progressions to be provided to Enterprise members under various circumstances, and the like. In an embodiment, Enterprise member database  178  may specify particular policy definitions in response to receipt of simulated IN triggers that originate from a member&#39;s mobile terminal as described more fully hereinbelow. 
     In accordance with an embodiment, GS-C  192  may be managed by an Intermediary carrier  190 , such as a mobile virtual network operator (MVNO). In this implementation, GS-C  192  is deployed or interconnected with carrier network  150  but is serviced by Intermediary carrier  190 . Accordingly, an MVNO may provide mobile services to global Enterprise Customers, e.g., by reselling carrier services, e.g., CDMA or GSM services, combined with Intermediary Carrier Enterprise offerings. Intermediary carrier  190  provides the ability to control HLR profiles of user to route simulated IN-triggers that are originated and processed according to embodiments disclosed herein as described more fully hereinbelow. Moreover, Intermediary carrier  190  may provide Intermediary carrier hosting services to CDMA carriers, such as hosting GS-C and offer Enterprise services for a monthly charge, provide international support for GS-C services as an option to an Enterprise, and the like. 
       FIG. 2  is a simplified block diagram of an exemplary mobile terminal  125  in which embodiments may be implemented. Mobile terminal  125  includes an antenna  202  that may be coupled with an RF switch  204 , e.g., a duplexer, coupled with an RF transceiver  206 . Transceiver  206  may be coupled with an analog baseband  208  that may handle a variety of analog signal processing functions. In the present example, analog baseband  208  is interconnected with a microphone  210 , a keypad  212 , a vibrator  214  or other ring alert mechanism, a headset speaker  216 , and a loudspeaker  230  for output of speakerphone and incoming call alert audio. Analog baseband  208  may include or interface with an analog to digital converter for converting analog input supplied to microphone  210  into a digital format that may be supplied to a digital baseband  218 . Digital baseband  218  may interface with various digital components of mobile terminal  125 , such as a memory  220 , a subscriber identity module (SIM)  222 , and a liquid crystal display controller  226  that drives a display  228 . Memory  220  may be implemented as a flash memory, a random access memory, an electronically erasable programmable read-only memory, another solid state device, or a combination thereof. Digital baseband  218  may additionally include or interface with one or more encoders, digital to analog converters, or other modules. An operating system (O/S)  234 A may interface with Analog Baseband  208 , and Digital Baseband  218  for enabling the execution of client software application  234 B. A power supply  232  may be coupled with various system modules as is understood. In accordance with an embodiment, an IN simulator is deployed on SIM  222  or client software application  234 B that is adapted to generate simulated IN triggers for provisioning of IN service functionality in a network system such as system  100  depicted in  FIG. 1 . 
     The implementation of mobile terminal  125  depicted in  FIG. 2  is exemplary only, and mobile terminal  125  may be implemented as any suitable device adapted to interface with a carrier network. Mobile terminal  125 , also referred to as a user equipment (UE), may be implemented as a personal digital assistant (PDA), a mobile phone, a computer, or another device adapted to interface with a carrier network. 
       FIG. 3  is a diagrammatic representation of an exemplary software configuration  300  of a mobile terminal, e.g., mobile terminal  125 , adapted for originating simulated IN triggers in accordance with an embodiment. In the exemplary configuration of  FIG. 3 , the mobile terminal is configured with access network-specific software entities  360 , e.g., protocol and driver software associated with a particular access network technology, such as GSM, UMTS, CDMA or another suitable radio access network, and is dependent on the particular cellular network in which the mobile terminal is to be deployed. While configuration  300  depicts a mobile terminal adapted for deployment in a single access network technology type, the mobile terminal may be implemented as a multi-mode device and may accordingly include a plurality of access-specific entities in accordance with an embodiment. The particular configuration  300  is illustrative only and is provided only to facilitate an understanding of embodiments disclosed herein. 
     In the illustrative example, configuration  300  includes a cellular modem driver  302  for providing a physical interface with the access network in which the mobile terminal is deployed. An access-stratum  304  and a non-access stratum  306  may be included in configuration  300 . A cellular radio interface  308  may be communicatively coupled with lower layers of configuration  300  and may additionally interface with network and session management layers, e.g., a network stack  310  such as a TCP/IP layer. 
     Configuration  300  includes an IN simulator  312  for providing IN service functionality in accordance with an embodiment. Additionally, configuration  300  includes an operating system  314 , such as Symbian, Blackberry O/S, or another operating system suitable for mobile applications, and may coordinate and provide control of various components within the mobile terminal. 
     In an embodiment, IN Simulator  312  is registered as a call observer function in mobile terminal  125 . Accordingly, mobile terminal  125  notifies IN Simulator  312  of call origination and termination events, and IN Simulator  312  may generate messages related to call origination and termination events that facilitate provisioning of IN services without the network support of IN triggers. Messages generated by IN Simulator  312  that facilitate provisioning of IN services are referred to herein as simulated IN triggers. 
     If a carrier network, e.g., GSM carrier network  150 , doesn&#39;t support a trigger infrastructure that has capabilities of originating triggers and terminating triggers—or if a roaming agreement is not in place that allows the transfer of these triggers between carriers—the use of IN Simulator  312  provides an alternative mechanism that provides the same information to an IN based application in accordance with an embodiment. IN Simulator  312  is thereby adapted to mimic the IN triggering infrastructure and provides mechanisms for implementing IN trigger service functionality without network support for IN triggers. 
     Various simulated trigger mechanism that are facilitated by IN Simulator  312  are described below. The described trigger mechanisms are illustrative only and are provided to facilitate an understanding of the disclosed embodiments, and implementation of embodiments disclosed herein is not restricted to the described triggers. 
     To create an IN-simulated origination trigger for Detection Point  2  (DP 2 ) “Collected Information” structure, the following steps may be performed. IN Simulator  312  is registered as a call observer function and receives the call origination event from the originating mobile terminal. IN Simulator  312  converts the origination request into a data message using a method such as USSD, SMS, GPRS or other mechanism that is sent to the IN-based application with the origination message parameters as appropriate. In the exemplary network architecture, the IN-based application may be run by GS-C  192  in conjunction with GS-E  176 . That is, the IN service progression is managed by at least one of GS-C  192  and GS-E  176 . The IN-based application run by GS-C  192  and/or GS-E  176  performs its application processing and returns the response to the simulated Origination Trigger via the data network such as USSD, SMS, etc. These responses may include Connect, Continue and Release. If the data message contains a Connect response, IN Simulator  312  will set up an originating call with the digits provided in the data message instead of the original dialed digits. If the data message contains a Continue response, IN Simulator  312  will set up an originating call to the original dialed string. If the data message contains a Release response, IN Simulator  312  can provide treatment such as providing a tone to the user or display a message indicating that the call could not be completed. 
     To create an IN-simulated origination trigger DP for an origin-Busy (“O-Busy”) structure the following general procedure may be performed. IN Simulator  312  is registered as a call observer function and receives the busy end point notification from the switching infrastructure. IN Simulator  312  converts the origination request into a data message, e.g., using USSD, SMS, etc., that is sent to the IN based application, e.g., run by GS-C  192 , with the origination message parameters as appropriate. The IN based application performs its application processing and returns the response to the Origination Trigger via a data message. 
     To create an IN-simulated origination trigger DP for an origin-No Answer (“O-No Answer”) structure, the following general procedure may be performed. IN Simulator  312  is registered as a call observer function and receives a disconnect notification from the network prior to the call being answered. IN Simulator  312  converts the origination request into a data message to the IN based application with the origination message parameters as appropriate. The IN based application performs its application processing and returns the response to the Origination Trigger via a data message. 
     To create an IN-simulated origination trigger DP for an origin-Answer (“O-Answer”) structure the following general procedure may be performed. IN Simulator  312  is registered as a call observer function and receives the answer indication from the switching network. IN Simulator  312  converts the origination request into a data message that is transmitted to the IN based application with the origination message parameters as appropriate. The IN based application performs its application processing and returns the response to the Origination Trigger via a data message. 
     To create an origination trigger DP for an origin-Disconnect (“O-Disconnect”) structure, the following general procedure may be performed. IN Simulator  312  is registered as a call observer function and receives the disconnect indication from the network or the end key input from the user. IN Simulator  312  converts the origination request into a data message that is transmitted to the IN based application run by the GS-C with the origination message parameters as appropriate. The IN based application performs its application processing and returns the response to the IN-simulated Origination Trigger via a data message. 
     To create an IN-simulated termination trigger DP 12  for “Terminating Attempt Authorized” the following general procedure may be performed. IN simulator  312  receives the call termination event from the mobile terminal. IN simulator  312  converts the call termination into a data message and transmits the data message to the IN based application with the termination message parameters as appropriate. The IN based application performs its application processing and returns the response to the IN-simulated Termination trigger via a data message. These responses may include Connect, Continue or Release. If the data message contains a Connect response, IN simulator  312  uses the Call Deflection Supplementary Service to redirect the call to the endpoint provided in the connect response. If the data message contains a Continue response, IN Simulator  312  allows the call to be delivered and proceeds to ring the mobile terminal. If the data message contains a Release response, IN Simulator  312  does not accept the call and terminates to switching infrastructure. 
     An IN-simulated Termination Trigger DP 13  for “Busy” can be created by IN Simulator  312  in the case when the IN based application infrastructure also provides an alternative to call waiting services. This is because a busy determination is typically handled by the switching infrastructure without any knowledge by the handset. However, this can be replicated by implementing an alternative call waiting service in accordance with an embodiment. The following procedure may generally be performed to create an IN-simulated DP 13  “Busy” trigger. IN Simulator  312  receives notification of a terminating call. A data message is sent to the IN application, and the IN application sends back a connect message to indicate to connect the call to the IN application. The data message received by IN simulator  312  contains the connect-to information. IN simulator  312  uses the Call Deflection Supplementary Service to redirect the call to the end point received in the connect response. The IN application, receiving the call termination, routes the call to the terminating mobile via the switching infrastructure. IN Simulator  312  will again receive notification of this terminating call from the IN application. The call should be presented to the user with the original calling line ID information provided. IN simulator  312  receives another notification during the current call. This call is not answered so that end point is receiving ringing. A data message is sent to the IN application. The IN application sends back a connect message to indicate to connect the call to the IN application. The data message received by IN simulator  312  contains the connect to information. IN simulator  312  uses the Call Deflection Supplementary Service to redirect the call to the end point received in the connect response. IN simulator  312  provides a call waiting indication to the user via a tone and the display of who is calling. If the user decides to accept the incoming call by pressing “send”, IN simulator  312  issues a data message to the IN application. When the IN application receives the message that the user wants to accept the new incoming call, it answers the new call and connects to the current leg that it has up to the mobile and places the current leg on hold. IN Simulator  312  receives notification of the terminating call while currently handling the two established calls. A data message is sent to the IN application, and the IN application sends back a connect message to indicate to connect the call to the IN application. The data message received by IN simulator  312  contains the connect to information. IN simulator  312  uses the Call Deflection Supplementary Service to redirect the call to the IN application. The IN application, receiving the call termination and knowing that the user is currently handling two calls—gives busy treatment to the new call and can create a DP- 13  to itself or other application requiring the DP- 13 . Busy trigger. 
     In accordance with an embodiment, an IN-simulated Terminating Trigger for DP 14  “No Answer” may be generated and processed according to two general procedures. A No Answer DP can occur in two ways—when the mobile is not registered on the network, and when the mobile rings but the user chooses not to answer. These two general scenarios are processed according to disclosed embodiments as follows. When the mobile terminal is not registered on the network, the call forwarding number of the mobile is set to the IN application When a call is received at the IN application, the IN application creates a no answer trigger for this received call. 
     When the mobile terminal is registered but the user doesn&#39;t answer the call, IN Simulator  312  is informed that a terminating call has been delivered to the phone and detects that the user has selected the end button when the call is “ringing”. In this instance, IN Simulator  312  generates and sends a data message to the IN application providing the IN-simulated No Answer Trigger. The IN application may then provide either a release or connect response to the termination trigger. If IN simulator  312  receives a connect response, IN simulator  312  uses the Call Deflection Supplementary Service to redirect the call to the IN application. If IN simulator  312  receives a release response, the call can be released from the switching infrastructure. 
     To create an IN-simulated termination trigger for DP 15  “Answer”, the following general procedure may be performed. IN simulator  312  receives the send or answer indication from the mobile terminal. IN simulator  312  converts the event into a data message to the IN-based application with the termination message parameters as appropriate. The IN based application performs it application processing and returns the response to the Termination trigger via a data message. 
     To create an IN-simulated termination trigger for DP 17  “Disconnect” the following general procedure may be performed. IN simulator  312  receives the end key or disconnect indication from the mobile terminal. IN simulator  312  converts the event in to a data message and sends the data message to the IN based application with the termination message parameters as appropriate. The IN based application performs its application processing and returns the response to the IN-simulated Termination trigger via a data message. 
     To create an IN-simulated termination trigger for DP 18  “Abandon” the following general procedure may be performed. IN simulator  312  receives the disconnect indication from the network prior to call answering state. IN simulator  312  converts the event in to a data message that is transmitted to the IN-based application with the termination message parameters as appropriate. The IN based application performs its application processing and returns the response to the IN-simulated Termination trigger via a data message. 
       FIG. 4  is a diagrammatic representation of a signaling flow  400  of a mobile originated call to an Enterprise member implemented in accordance with an embodiment. In the present example, assume the originating mobile terminal  125  is equipped with an instance of IN Simulator  312  described with reference to  FIG. 3 , and that the user of mobile terminal  125  uses abbreviated dialing for calling User 2&#39;s Enterprise telephone device  172   a . That is, User 1 placing the call dials User 2&#39;s Enterprise extension rather than the full directory number assigned to device  172   a . Upon entry of the dialed number and a call setup command, e.g., by selecting Send at mobile terminal  125 , IN simulator  312  identifies the call origination event. IN simulator  312  then collects the call information suitable for generating an IN-simulated origination trigger (DP  2 ), and creates an IN-simulated DP  2  trigger from the collected call information. In the illustrative example, the collected information corresponding to a DP  2  trigger is formulated in a USSD message. The USSD message is then transmitted through the radio access network, e.g., via BTS  158   a  and BSC  157 , wherein the USSD message is received at MSC  153  (step  402 ). MSC  153  accordingly routes the USSD message to USSD gateway  163  (step  404 ) that in turn forwards the USSD message to GS-C  192  (step  406 ). Thus, in this manner, the collected information formulated in the USSD message is transmitted to GS-C  192  in a manner that replaces a trigger event detected at an SSP. Accordingly, carrier network  150  is not required to support the IN infrastructure or, alternatively, mobile terminal  125  is not required to have any IN service agreement with carrier network  150  for invoking an IN service function. 
     On receipt of the USSD message, GS-C  192  may recognize the called or calling party as an Enterprise member and issue an INVITE message to GS-E  176  (step  408 ). GS-E  176  may query Enterprise member database  178  to determine an appropriate call progression, e.g., whether to release the call, terminate the call with the dialed party&#39;s fixed enterprise telephony device, the dialed party&#39;s mobile terminal, or other suitable call progression. In the present example, assume GS-E  176  replies to GS-C  192  with a SIP redirection, e.g., a SIP 302 message, that includes a redirection address, e.g., a pilot directory number (PDN) assigned to device  172   a  (step  410 ). GS-C  192 , in turn, includes the PDN in a USSD message that is transferred to USSD gateway  163  (step  412 ) which routes the USSD to mobile terminal  125  (step  414 ). 
     The USSD including the PDN is then conveyed to IN simulator  312  which invokes an outbound call at mobile terminal  125  directed to the PDN (step  416 ). MSC, on receipt of the call setup request, determines the PDN to be a directory number external to carrier network  150  and routes the call set up to GMSC  151  (step  418 ), GSMC  151  recognizes the PDN as a pilot number of PBX  171  and routes the call termination attempt thereto (step  420 ). PBX  171  may then issue an INVITE message with the PDN as the called party directory number to GS-E  176  (step  422 ). GS-E  176  resolves the user directory number associated with the PDN and replies to PBX  171  (step  424 ), e.g., with the extension assigned to User 2&#39;s land line telephony device  172   a . The call set up is then completed with device  172   a  (step  426 ). 
       FIG. 5  is a diagrammatic representation of a signaling flow  500  of an Enterprise member placing a call to another enterprise member from an enterprise landline telephony device  172   a  implemented in accordance with an embodiment. Assume for illustrative purposes that the called number is supplied as the short code, or extension, of Enterprise telephony device  172   n  assigned to User 1, and that the call is placed at Enterprise telephony device  172   a . The call set up request is transmitted from device  172   a  to PBX  171  (step  502 ), which in turn transmits a telephone application program interface (TAPI) function call to GS-E  176  (step  504 ). In accordance with an embodiment, GS-E  176  may maintain or interface with a record allocated for called User 1 that associates the directory number of Enterprise telephony device  172   n , the short code of device  172   n , and the directory number of mobile terminal  125 . In this instance, the call may be “forked” or generally placed in parallel to the called Enterprise telephony device as well as mobile terminal  125  associated with the called user. To this end, an INVITE message is transmitted from GS-E  176  to PBX  171  that specifies the extension of device  172   n  (step  506 ). The INVITE may then be transmitted to device  172   n  (step  508 ). 
     A second INVITE message may be generated and transmitted from GS-E  176  to GS-C  192  that specifies the directory number of mobile terminal  125  (step  510 ). Transmission and generation of the INVITE message that specifies mobile terminal  125  may be made substantially concurrently with the INVITE message transmitted toward the Enterprise landline telephony device  172   n . GS-C  192  may then transmit a send routing information (SRI) message to HLR  154  that maintains subscription records of mobile terminal  125  (step  512 ). HLR  154  then identifies the servicing MSC  153  of mobile terminal  125  and transmits a provide roaming number (PRN) message thereto (step  514 ). MSC  153  then transmits a PRI response message to HLR  154  that includes the mobile station roaming number assigned to mobile terminal  125  (step  516 ) which is forwarded to GS-C  192  (step  518 ). GS-C  192  then transmits a SIP redirection message that includes the mobile station roaming number of mobile terminal  125  as a temporary local directory number (TLDN) to GS-E  176  (step  520 ). An INVITE message is then transmitted to PBX  171  (step  522 ) that includes the TLDN number that allows PBX  171  to complete the call setup through GMSC  151  which uses the TLDN for routing the call to mobile terminal  125  via the appropriate MSC  153  (step  524 ). Accordingly, both devices  125  and  172   n  may provide an incoming call alert, and User 1 assigned devices  125  and  172   n  may accept the call at either device. 
       FIG. 6  is a diagrammatic representation of a signaling flow  600  of a call originated from a PSTN device  625  to an Enterprise member in accordance with an embodiment. Assume for illustrative purposes that the called number is the directory number assigned to landline device  172   n  assigned to User 1. The call set up request is transmitted from device  625  to PBX  171  (step  602 ), which in turn transmits a TAPI function call to GS-E  176  (step  604 ). GS-E  176  may evaluate the dialed number and identify mobile terminal  125  as being associated with landline device  172   n . That is, GS-E  176  may identify mobile terminal  125  and device  172   n  as both assigned to the called Enterprise member, and may determine the directory number of mobile terminal  125 . Thus, GS-E  176  may facilitate establishing a call origination to both landline device  172   n  and mobile terminal  125 . To this end, GS-E  176  transmits an INVITE message to PBX  171  that specifies the extension of device  172   n  (step  606 ), and PBX  171  provides an alert to device  172   n  (step  608 ). 
     A second INVITE message may be generated and transmitted from GS-E  176  to GS-C  192  that specifies the directory number of mobile terminal  125  (step  610 ). Transmission and generation of the INVITE message that specifies mobile terminal  125  may be made substantially concurrently with the INVITE message transmitted toward the Enterprise network for alerting device  172   n  of an incoming call. GS-C  192  may then transmit an SRI message to HLR  154  that maintains subscription records of mobile terminal  125  (step  612 ). HLR  154  then identifies the servicing MSC  153  of mobile terminal  125  and transmits a PRN message thereto (step  614 ). MSC  153  then transmits a PRN response message to HLR  154  that includes the mobile station roaming number assigned to mobile terminal  125  (step  616 ) which is forwarded to GS-C  192  (step  618 ). GS-C  192  then transmits a SIP redirection message that includes the mobile station roaming number of mobile terminal  125  as a temporary local directory number (TLDN) to GS-E  176  (step  620 ). An INVITE message is then transmitted to PBX  171  (step  622 ) that includes the TLDN number that allows PBX  171  to complete the call setup through GMSC  151  which uses the TLDN for routing the call to mobile terminal  125  via the appropriate MSC  153  (step  624 ). Accordingly, both devices  172   n  and  125  assigned to the called Enterprise member, User 1, have a termination attempt placed thereto. 
       FIG. 7  is a diagrammatic representation of a signaling flow  700  of a call originated from a PSTN device  725  to an Enterprise member in accordance with an embodiment. In the illustrative example, assume the dialed number is assigned to an Enterprise member&#39;s mobile terminal  125 . The call set up request is transmitted from device  725  to GMSC  151  (step  702 ), which in turn forwards the call request to MSC  153  currently servicing mobile terminal  125  (step  704 ). In the present example, assume mobile terminal  125  is configured with an IN Simulator  312 . Accordingly, on receipt of the call termination attempt at mobile terminal  125 , IN Simulator  312  receives or is otherwise notified of the call termination event. In accordance with an embodiment, IN Simulator  312  may be configured to recognize that carrier network  150  does not support IN triggers, or that IN triggers or otherwise unavailable for mobile terminal  125 , e.g., by a lack of a suitable agreement with carrier network  150 . IN simulator  312  may then temporarily suppress or otherwise prohibit an incoming call alert notification at mobile terminal  125 . IN Simulator  312  collects event information suitable for creating an IN-simulated DP  12  trigger in the form of a data message, e.g., a USSD message, that is to be transmitted to the IN based application hosted by GS-C  192  with the termination message parameters as appropriate. The USSD message is then transmitted through the radio access network to USSD gateway  163  (step  708 ) that in turn forwards the USSD message to GS-C  192  (step  710 ). Thus, in this manner, the collected information formulated in the USSD message is transmitted to GS-C  192  in a manner that replaces a conventional IN trigger. Accordingly, carrier network  150  is not required to support the IN infrastructure or, alternatively, mobile terminal  125  is not required to have any IN service agreement with carrier network  150  for invoking an IN service. 
     On receipt of the USSD message, GS-C  192  may recognize the called party as an Enterprise member and issue an INVITE message to GS-E  176  (step  712 ) and may await receipt of a response as to how to proceed with the call. GS-E  176  may query Enterprise member database  178  to determine an appropriate call progression, e.g., whether to terminate the call with the dialed party&#39;s fixed enterprise telephony device, the dialed party&#39;s mobile terminal, or other suitable call progression. In the illustrative example, assume GS-E  176  replies to GS-C  192  with a policy allowance, e.g., via a SIP 302 message with a Continue directive (step  714 ). The determination of a policy allowance by GS-E  176  may be made, for example, according to the called Enterprise member&#39;s profile or according to a general Enterprise behavior. GS-C  192 , in turn, formulates a USSD message addressed to mobile terminal  125  that is transferred to USSD gateway  163  which includes a directive to continue with the call (step  716 ) which routes the USSD message to mobile terminal  125  (step  718 ). The USSD message is conveyed to IN Simulator  312  which reads the Continue directive therefrom. Accordingly, IN Simulator  312  invokes processing to continue with the call termination at which point an alert is generated, e.g., by IN Simulator  312 , to notify the user of the incoming call. The call termination may then be completed when the call is accepted at mobile terminal  125 . 
       FIG. 8  is a diagrammatic representation of a signaling flow  800  of a call originated from a PSTN device  825  to an Enterprise member in accordance with an embodiment. In the illustrative example, assume the dialed number is assigned to an Enterprise member&#39;s mobile terminal  125 . The call set up request is transmitted from device  825  to GMSC  151  (step  802 ), which in turn forwards the call request to MSC  153  currently servicing mobile terminal  125  (step  804 ). In the present example, assume mobile terminal  125  is configured with an IN Simulator  312 . Accordingly, on receipt of the inbound call attempt at mobile terminal  125 , IN Simulator  312  receives or is otherwise notified of the call termination event. In accordance with an embodiment, IN Simulator  312  may be configured to recognize that carrier network  150  does not support IN triggers, or that IN triggers or otherwise unavailable for mobile terminal  125 . IN simulator  312  may then temporarily suppress or otherwise prohibit an incoming call alert notification at mobile terminal  125 . IN Simulator  312  collects event information suitable for creating an IN-simulated DP  12  trigger in the form of a data message, e.g., a USSD message, to the IN based application with the termination message parameters as appropriate. The USSD message is then transmitted through the radio access network to USSD gateway  163  (step  808 ) that in turn forwards the USSD message to GS-C  192  (step  810 ). GS-C  192  hosts an IN based application that performs application processing and returns the response to the IN-simulated Termination trigger via a data message. These responses may include Connect, Continue or Release. Thus, in this manner, the collected information formulated in the USSD message is transmitted to GS-C  192  in a manner that replaces a conventional IN trigger. Accordingly, carrier network  150  is not required to support the IN infrastructure or, alternatively, mobile terminal  125  is not required to have any IN service agreement with carrier network  150  for invoking an IN service. 
     On receipt of the USSD message, GS-C  192  may recognize the called party as an Enterprise member and issue an INVITE message to GS-E  176  (step  812 ) and await call processing instructions therefrom. GS-E  176  may determine a policy for processing the call, e.g., release, continue, or connect the call based on, for example, the called Enterprise member&#39;s profile. To this end, GS-E  176  may query Enterprise member database  178  to determine an appropriate call progression, e.g., whether to allow or disallow the call, whether to terminate the call with the dialed party&#39;s fixed Enterprise telephony device, the dialed party&#39;s mobile terminal, or other suitable call progression. In the illustrative example, assume GS-E  176  replies to GS-C  192  with a policy allowance, e.g., via a SIP 302 message (step  814 ). In the present example, assume the policy allowance message transmitted from GS-E  176  to GS-C  192  includes a directive to continue with the call, and that the call is to be redirected through Enterprise network  170 . To this end, the reply provided to GS-C  192  from GS-E  176  will include a PDN to which the call is to be deflected. GS-C  192 , in turn, formulates a USSD message addressed to mobile terminal  125  that is transferred to USSD gateway  163  which includes a call deflect directive (step  816 ) which routes the USSD message to mobile terminal  125  (step  818 ). The USSD message is conveyed to IN Simulator  312  which reads the call deflect directive and PDN therefrom. IN Simulator  312  then initiates the call deflection procedure, e.g., by transmitting a Call Deflection Invoke message that includes the PDN as the Deflect To Number to MSC  153  (step  820 ). In the present example, the PDN number is recognized as associated with PBX  171 . Accordingly, the call termination attempt is routed to PBX  171  (step  820 ), at which point a termination attempt may be made with telephony device  172   n  associated with User 1 (step  822 ). Likewise, a termination attempt may additionally be made to mobile terminal  125  that is redirected from Enterprise network  170  back to mobile terminal  125  (step  824 ). 
       FIG. 9  is a diagrammatic representation of a signaling flow  900  of a call originated from an Enterprise member (User 1) mobile terminal  125  to another Enterprise member (User 2) implemented in accordance with an embodiment. In the illustrative example, assume mobile terminal  125  is adapted with an IN Simulator  312  and the dialed number is assigned to the called party&#39;s Enterprise landline telephone device  172   a . Upon entry of the dialed number and a call setup command, e.g., by selecting Send at mobile terminal  125 , IN simulator  312  identifies the call origination event. IN simulator  312  then collects the call information suitable for generating an IN-simulated origination trigger DP  2 , and creates a simulated DP  2  trigger from the collected information. In the illustrative example, the collected information corresponding to a DP  2  trigger is formulated in a USSD message. The USSD message is then transmitted through the radio access network, e.g., via BTS  158   a  and BSC  157 , wherein the USSD message is received at MSC  153  (step  902 ). MSC  153  accordingly routes the USSD message to USSD gateway  163  (step  904 ) that in turn forwards the USSD message to GS-C  192  (step  906 ). GS-C  192  hosts an IN based application that performs application processing and returns the response to the IN-simulated Termination trigger via a data message. These responses may include Connect, Continue or Release. 
     On receipt of the USSD message, GS-C  192  may recognize the party as an Enterprise member and communicate the call origination to GS-E  176  (step  908 ). GS-E  176  may query Enterprise member database  178  to determine an appropriate call progression, e.g., to connect, continue, or release the call, and if the call is to be connected, whether to connect the call with the dialed party&#39;s fixed enterprise telephony device, the dialed party&#39;s mobile terminal or other alternative. In the illustrative example, assume the mobile terminal is currently operating at an international carrier or other carrier for which mobile terminal  125  faces long distance charges for terminating the call. In this instance, GS-E  176  may recognize mobile terminal  125  as having roamed into an international carrier or other carrier for which long distance charges may apply. Accordingly, GS-E  176  may reply to GS-C  192  with a call back response (step  910 ). GS-C  192  formulates a USSD message that includes the call back directive and transmits the USSD message to USSD gateway  163  (step  912 ) which, in turn, forwards the USSD message to mobile terminal  125  (step  914 ). The Call Back directive is read from the USSD message by IN Simulator  312 . IN Simulator  312  is configured to recognize the Call Back directive and place mobile terminal  125  in a wait state. 
     Prior, subsequent, or substantially concurrent with the generation and transmission of the response from GS-E  176  to GS-C  192  at step  910 , GS-E  176  may transmit an INVITE message to PBX  171  that is transmitted to Enterprise device  172   a , that is the device to which the original call was placed (step  918   a ), which conveys the call termination attempt to device  172   a  (step  920   a ). Substantially concurrently with transmission of the INVITE message directed to device  172   a , a second INVITE message addressed to mobile terminal  125  that originated the call is transmitted from GS-E  176  to PBX  171  (step  918   b ), which in turn conveys the termination attempt to mobile terminal  125  (step  920   b ). On receipt of the termination attempt at mobile terminal  125 , IN Simulator  312  may be configured to recognize the inbound call as a call back for the previously placed call, and IN Simulator  312  may be configured to output a ringback tone, rather than a ring tone associated with an inbound call. Thus, from a user perspective, the inbound call termination appears as an outbound call consistent with the call placement made by the user of mobile terminal  125 . Alternatively, the ringback tone may be generated upon transmission of the USSD message at step  902  and continued throughout the call back procedure until the called party answers the call at device  172   a . Accordingly, the calling party may be connected with the called party through the call back procedure, and international charges for the call may be substantially lower by receiving a call termination fee, rather than a call origination fee, applied for the roaming terminal  125 . 
     As described, embodiments disclosed herein provide mechanisms for simulating IN triggers in a network system. A mobile terminal may be configured with an IN Simulator that is adapted to originate simulated IN triggers, for example in the form of USSD messages, SMS messages, or another suitable data structure. Call progressions implemented according to the simulated IN triggers may be managed or coordinated by at least one of a carrier-gateway server and an Enterprise-gateway server. Call progressions implemented by the simulated IN triggers may be specified according to Enterprise member policies or general Enterprise behaviors. The IN Simulator may be deployed on a mobile terminal SIM or on a mobile terminal capable of supporting a software client and is registered as a call observer function. The IN Simulator is adapted to generate simulated IN triggers for provisioning of IN service functionality in the network. The IN Simulator may generate messages related to call origination and termination events that facilitate provisioning of IN services without the network support of conventional IN triggers. Advantageously, if a carrier network does not support a trigger infrastructure that has capabilities of originating triggers and terminating triggers—or if a roaming agreement is not in place that allows the transfer of these triggers between carriers—the use of an IN Simulator provides an alternative mechanism that provides the information to a IN based application for providing IN service functionality without network support for IN triggers. 
     Although the specific network architecture and nomenclature in which a mobile terminal featuring an IN Simulator are depicted and described according to the GSM, it is understood that this is done so for illustrative purposes only and that the network architecture on which embodiments disclosed herein may be applied is not limited to any particular standard, but rather may be equivalently implemented on any other communications system supporting any variety of cellular communication systems, e.g. D-AMPS, CDMA, IS-41, ANSI-41, UMTS, etc. 
     The illustrative block diagrams depict process steps or blocks that may represent modules, segments, or portions of code that include one or more executable instructions for implementing specific logical functions or steps in the process. Although the particular examples illustrate specific process steps or procedures, many alternative implementations are possible and may be made by simple design choice. Some process steps may be executed in different order from the specific description herein based on, for example, considerations of function, purpose, conformance to standard, legacy structure, user interface design, and the like. 
     Aspects of the present invention may be implemented in software, hardware, firmware, or a combination thereof. The various elements of the system, either individually or in combination, may be implemented as a computer program product tangibly embodied in a machine-readable storage device for execution by a processing unit. Various steps of embodiments of the invention may be performed by a computer processor executing a program tangibly embodied on a computer-readable medium to perform functions by operating on input and generating output. The computer-readable medium may be, for example, a memory, a transportable medium such as a compact disk, a floppy disk, or a diskette, such that a computer program embodying the aspects of the present invention can be loaded onto a computer. The computer program is not limited to any particular embodiment, and may, for example, be implemented in an operating system, application program, foreground or background process, driver, network stack, or any combination thereof, executing on a single computer processor or multiple computer processors. Additionally, various steps of embodiments of the invention may provide one or more data structures generated, produced, received, or otherwise implemented on a computer-readable medium, such as a memory. 
     Although embodiments of the present disclosure have been described in detail, those skilled in the art should understand that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.