Abstract:
A method and an apparatus are provided for processing a Circuit-Switched (CS) call by User Equipment (UE) that is camped on a CSG cell, when a manually selected CSG cell is in a Public Land Mobile Network (PLMN), which is different from a Registered PLMN (RPLMN). The method includes registering, by the UE, with a manually selected Closed Subscriber Group (CSG) cell of a Public Land Mobile Network (PLMN), which is different from a Registered PLMN (RPLMN) of the UE; detecting the CS call; and processing the CS call in a non-CSG cell, when the manually selected CSG cell is unable to process the CS call.

Description:
PRIORITY 
       [0001]    This application claims priority under 35 U.S.C. §119(a) to Indian Provisional Application Number 1307/CHE/2014, which was filed in the Indian Intellectual Property Office on Mar. 12, 2014, and Indian Complete Application Number 1307/CHE/2014, filed on Nov. 19, 2014 in the Indian Intellectual Property Office, the disclosure of each of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field of the Disclosure 
         [0003]    The present disclosure relates to a method and apparatus for processing a Circuit-Switched (CS) call by a User Equipment (UE) that is camped on a manually selected Closed Subscriber Group (CSG) cell. 
         [0004]    2. Description of the Related Art 
         [0005]    The Third (3 rd ) Generation Partnership Project (3GPP) defines a Closed Subscriber Group (CSG), which identifies subscribers of a service provider that are permitted to access a cell of a Public Land Mobile Network (PLMN), but which may have restricted access. More specifically, a CSG cell is accessible by members of the CSG, using a CSG Identity (CSG ID). 
         [0006]    In a manual mode of CSG selection, a user of the UE selects a CSG cell. Specifically, the UE scans for available CSG cells, from which the user manually selects a CSG cell. The UE behavior may be differentiated based on whether the selected CSG cell belongs to a Registered PLMN (RPLMN) or to a different PLMN. 
         [0000]    non-volatile memory. Further, upon successful registration on the selected CSG cell, the RPLMN is not updated with that of the selected PLMN. 
         [0007]    For example, when the UE is camped on the selected CSG cell, which belongs to a PLMN that is different than the RPLMN, and a CS call is initiated by a user the UE, the UE sends an Extended Service Request (ESR) to the PLMN of the manually selected CSG cell. However, because the manually selected PLMN is different from the RPLMN, the PLMN of the manually selected CSG cell may send a Redirection Request to the UE. The Redirection Request requests the UE to camp on a 3G/2G cell associated with the PLMN of the manually selected CSG cell or another PLMN in the network. 
         [0008]    Based on the redirection request, the UE moves out of the currently camped CSG cell and initiates a cell search procedure for the 3G/2G cell on the PLMN associated with the manually selected CSG cell or the another PLMN in the network. 
         [0009]    In current systems, when the UE moves out of manually camped CSG Cell (or when the UE loses the coverage of the user selected CSG cell), the UE changes the PLMN selection mode back to the PLMN selection mode saved prior to the manual CSG selection, and attempts recovery with the saved duplicate value of RPLMN. Hence, the CS call initiated by the user may not be processed by the UE, when the UE attempts recovery with the saved duplicate value of RPLMN (e.g., when UE moves out of currently camped CSG cell). 
         [0010]    If the CS call is processed at the UE by camping on the 3G/2G cell of the same PLMN or a different PLMN, the UE returns to the stored duplicate value of the RPLMN, upon the termination of the CS call. 
         [0011]    In the current systems, after the processing of the CS call, the user may have to manually select the CSG cell in order to camp on and re-register with the previously selected CSG cell. Accordingly, there is need for an easier method to camp on and re-register with the manually selected CSG cell. 
       SUMMARY 
       [0012]    Accordingly, the present disclosure has been made to address at least the problems and/or disadvantages described above and to provide at least the advantages described below. 
         [0013]    An aspect of the present disclosure is to provide a method and system for processing a CS call by a UE that is camped on a manually selected CSG cell. 
         [0014]    Another aspect of the present disclosure is to provide a method and system for camping on and registering with a manually selected CSG cell, after processing a CS call by the UE. 
         [0015]    In accordance with an aspect of the present disclosure, a method is provided for processing a CS call by a UE. The method includes registering, by the UE, with a manually selected Closed Subscriber Group (CSG) cell of a Public Land Mobile Network (PLMN), which is different from a Registered PLMN (RPLMN) of the UE; detecting the CS call; and processing the CS call in a non-CSG cell, when the manually selected CSG cell is unable to process the CS call. 
         [0016]    In accordance with another aspect of the present disclosure, a UE is provided for processing a CS call. The UE includes a memory; and a controller configured to register the UE with a manually selected Closed Subscriber Group (CSG) cell of a Public Land Mobile Network (PLMN), which is different from a Registered PLMN (RPLMN) of the UE; detect the CS call; and process the CS call in a non-CSG cell, when the manually selected CSG cell is unable to process the CS call. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The other aspects, features, and advantages of certain embodiments of the present disclosure will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0018]      FIG. 1  illustrates a wireless network in which a UE processes a CS call while being camped on a manually selected CSG cell, according to an embodiment of the present disclosure; 
           [0019]      FIG. 2  is a block diagram illustrating a UE, according to an embodiment of the present disclosure; 
           [0020]      FIG. 3  is a flow diagram illustrating a method for processing a CS call by a UE that is camped on a manually selected CSG cell, according to an embodiment of the present disclosure; 
           [0021]      FIG. 4A  is a signal flow diagram illustrating message signaling between a UE and to PLMNs for processing a Mobile Originated (MO) CS call, while the UE is camped on a manually selected CSG cell, according to an embodiment of the present disclosure; 
           [0022]      FIG. 4B  is a signal flow diagram illustrating message signaling between a UE and PLMNs for camping on and registering with a manually selected CSG cell, after processing an MO CS call, according to an embodiment of the present disclosure; 
           [0023]      FIG. 5A  is a signal flow diagram illustrating message signaling between a UE and PLMNs for processing a Mobile Terminated (MT) CS call, while the UE is camped on a CSG cell, according to an embodiment of the present disclosure; and 
           [0024]      FIG. 5B  is a signal flow diagram illustrating message signaling between a UE and PLMNs for camping on and registering with a CSG cell, after processing an MT CS call, according to an embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0025]    Various embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. In the following description, specific details such as detailed configuration and components are merely provided to assist the overall understanding of these embodiments of the present disclosure. Therefore, it should be apparent to those skilled in the art that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
         [0026]    The description may refer to “an”, “one” or “some” embodiment(s) in several locations, which does not necessarily imply that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. 
         [0027]    As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes”, “comprises”, “including” and/or “comprising” when used in this specification, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations and arrangements of one or more of the associated listed items. 
         [0028]    The embodiments herein provide a method and an apparatus for processing a CS call by a UE that is camped on a manually selected CSG cell. The method includes detecting the CS call, when the UE is registered with the manually selected CSG cell. The manually selected CSG cell is in a PLMN different from an RPLMN. The CS call can be either a Mobile Originated (MO) call or a Mobile Terminated (MT) call. 
         [0029]    When the UE detects the CS call, the UE sends an Extended Service Request (ESR) to the manually selected CSG cell. The UE receives a redirect request message from the manually selected CSG cell in response to the ESR. The redirect message indicates the UE to camp on a 3G/2G belonging to the PLMN of the manually selected CSG cell or a different PLMN by initiating a Circuit Switched Fall Back (CSFB) procedure. The non-CSG cell supports one or more services including, but not limited to, a Global System for Mobile communications (GSM) Edge Radio Access Network (GERAN) and Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN). The UE camps on the non-CSG cell of the PLMN of the manually selected CSG cell or a different PLMN for processing the CS call. For example, the non-CSG cell can be a macro cell. 
         [0030]    When the CS call is processed or the CS call is ended by the UE, the UE initiates a search to identify the manually selected CSG cell using pre-stored parameters. For example, the pre-stored parameters include an Evolved UTRA (EUTRA) Absolute Radio Frequency Channel Number (EARFCN), a CSG Identifier (ID), a cell ID, etc. If the UE identifies the manually selected CSG cell, as a result of the search, then the UE camps on and registers with the manually selected CSG cell. When the manually selected CSG cell is unavailable, as a result of the search, then the UE camps on and registers with the RPLMN using a stored duplicate value of the RPLMN. 
         [0031]    Unlike the conventional system, a proposed method and apparatus herein process the CS call, while the UE is camped on the CSG cell selected by the user. The CS call (including an Emergency call) is processed by the UE in the non-CSG cell by initiating the CSFB procedure, as opposed to the conventional system, where the CS call is dropped at the UE (e.g., upon the loss of coverage of the manually selected CSG cell). 
         [0032]    When the CS call is processed, the UE camps on and registers with the manually selected CSG cell, instead of camping on the RPLMN. When the manually selected CSG cell is unavailable to the UE, the UE camps on and registers with the RPLMN using the stored duplicate value of the RPLMN. 
         [0033]      FIG. 1  illustrates a wireless network in which a UE processes a CS call while being camped on a manually selected CSG cell, according to an embodiment of the present disclosure. 
         [0034]    Referring to  FIG. 1 , the wireless network  100  includes a PLMN  100   a , a PLMN  100   b , a UE  102 , a CSG  104   a , a CSG  104   b , and a CSG  104   c , which are associated with the PLMN  100   b , and a plurality of non-CSG cells  106   a ,  106   b , and  106   c . The non-CSG cell  106   a  is associated with the PLMN  100   b  and the non-CSG cells  106   b  and  106   c  are associated with the PLMN  100   a.    
         [0035]    For example, the UE  102  may be a cell phone, a personal digital assistant (PDA), a mobile personal computer, a laptop, a tablet, a phablet, a desktop computer, a communicator, etc. 
         [0036]    The UE  102  can be registered with the PLMN  100   a . Further, the PLMN  100   a  serving the UE  102  is commonly known as a Registered PLMN (RPLMN). Examples of services provided to the UE  102  by the RPLMN may include but are not limited to GERA (2G) services, UTRA (3G) services, and EUTRA (4G) services. 
         [0037]    The CSG cells  104   a ,  104   b , and  104   c  may further provide the UTRA (3G) services and EUTRA (LTE or 4G) services, as allowed by the network operator, i.e., PLMN  100   b . When the UE  102  is registered with the PLMN  100   a , and if the UE  102  enters an overlapping coverage area of CSG cells  104   a ,  104   b , and  104   c , the user can select any of the available CSG cells  104   a ,  104   b , and  104   c  by initiating a manual CSG selection request. 
         [0038]    During the manual CSG selection, the UE  102  scans all of the available CSG cells within its coverage area and provides a list of CSG cells to the user. For example, the list includes a plurality of detected CSG cells and the services (3G and 4G) supported by the detected CSG cells. The user can select any of the detected CSG cells from the CSG list. The UE  102  reselects the user selected CSG cell, after the user selected CSG cell accepts an attach request sent by the UE  102 . The UE  102  registers with the CSG cell for obtaining the services from the CSG cell belonging to the PLMN  100   b , which is different from the RPLMN, i.e., PLMN  100   a.    
         [0039]    For example, when the UE  102  is registered with the CSG cell  104   a , if a user initiates a CS call (MO call), then the UE  102  sends the ESR to the manually selected CSG cell  104   a.    
         [0040]    In response to the ESR, the UE  102  receives the redirect request message from the manually selected CSG cell  104   a . The redirect request message from the CSG cell  104   a  requests the UE  102  to initiate a CSFB procedure in the PLMN  100   b  or in the PLMN  100   a  for processing the CS call. The non-CSG cell  106   a  supports a plurality of services including, but not limited to, the GERA (2G) and the UTRA (3G) services. 
         [0041]    For the MT call, the UE  102  receives a paging message indicating the CS call from the manually selected CSG cell  104   a , before sending the ESR to the manually selected CSG cell  104   a.    
         [0042]    The UE  102  selects a non-CSG cell (either a 2G cell or a 3G cell) in the PLMN  100   b  or PLMN  100   a  for processing the CS call. For example, the UE  102  selects the non-CSG cell  106   a , e.g., a macro cell, in the PLMN  100   b  for processing the CS call. 
         [0043]    When the CS call is ended, the UE  102  initiates the search for identifying the manually selected CSG cell  104   a . In an embodiment, the UE  102  initiates the search for the manually selected CSG cell  104   a  using pre-stored parameters such as the EARFCN, the CSG ID, and/or the cell ID. If the UE  102  determines that the CSG cell  104   a  is available, as a result of the search, then the UE  102  camps on and registers with the manually selected CSG cell  104   a.    
         [0044]    If the UE  102  determines that the manually selected CSG cell  104   a  is unavailable, as a result of the search, then the UE  102  camps on and registers with the PLMN  100   a , which is the RPLMN of the UE  102 . Specifically, the UE  102  camps on and registers with the PLMN  100   a  using the stored duplicate value of the RPLMN (i.e., PLMN  100   a ). 
         [0045]    When the CS call is ended, the UE  102  camps on and registers with the manually selected CSG cell  104   a  using the pre-stored parameters of the manually selected CSG cell  104   a , without moving to the RPLMN using the stored duplicate value of the RPLMN. 
         [0046]      FIG. 2  is a block diagram illustrating a UE, according to an embodiment of the present disclosure. 
         [0047]    Referring to  FIG. 2 , the UE  102  includes a communication interface module  202 , a controller module  204 , a display module  206 , and a memory module  208 . 
         [0048]    The communication interface module  202  is configured to connect the UE  102  to a wireless network. 
         [0049]    The controller module  204  is configured to facilitate access control in the UE  102 . For example, during a manual CSG selection mode, the controller module  204  is configured to obtain a CSG list by scanning the available CSG cells within the coverage area of the UE  102 . The controller module  204  is configured to perform one or more actions for processing the CS call, when the UE  102  is registered with the CSG cell  104   a  on the PLMN  100   b.    
         [0050]    The display module  203  is configured to display a CSG list to the user. The CSG list includes a plurality of available CSG cells and services supported by the available CSG cells. For example, the user may select the CSG cell  104   a  from the CSG list, which can be displayed as a User Interface (UI) through the display module  206 . 
         [0051]    The display module  206  of the UE  102  may include the UI, e.g., a touch screen keypad through which the user can interact with the UE  102 . Accordingly, the display module  206  may be configured to receive a user input selecting a CSG cell from the CSG list. 
         [0052]    The memory module  208  may be a non-volatile memory or another type of dynamic storage device that stores information and instructions, e.g., an application for execution by a processor, a read-only memory (ROM) device, or another type of static storage device. 
         [0053]    In an embodiment, the memory module  208  is configured to store one or more parameters associated with the manually selected CSG cell, such as but not limited to the EARFCN, the CSG ID, and/or the cell ID. 
         [0054]    In an embodiment, the memory module  208  is configured to store the duplicate value of the RPLMN, which is used for connecting to the RPLMN, when the manually selected CSG cell is unavailable. 
         [0055]      FIG. 3  is a flow diagram illustrating a method  300  for processing a CS call by a UE that is camped on a CSG cell, according to an embodiment of the present disclosure. Specifically, the method illustrated in  FIG. 3  provides a basis for a control program, which can be implemented using a microcontroller, microprocessor, or any computer readable storage medium. Referring to  FIG. 3 , assuming the UE  102  is registered with the PLMN  100   a  (i.e., the RPLMN), when the UE  102  enters the coverage area of CSG cells  104   a ,  104   b  and  104   c , a user of the UE  102  can select any of the available CSG cells  104   a ,  104   b , and  104   c , by initiating a manual CSG selection request. The UE  102  reselects to the user selected CSG cell, e.g., CSG cell  104   a , when the user selected CSG cell  104   a  accepts an attach request sent by the UE  102 . The UE  102  registers with the CSG cell  104   a  for obtaining the services from the CSG cell  104   a  of the PLMN  100   b , different from the RPLMN  100   a . The method  300  for processing the CS call when the UE is registered with the manually selected CSG cell  104   a  is as described herein. 
         [0056]    In step  302 , the method  300  includes detecting the CS call when the UE  102  is registered with the manually selected CSG cell  104   a  of a different PLMN  100   b . The method  300  allows, e.g., the controller module  204 , detects a CS call while the UE is registered with the manually selected CSG cell  104   a . For example, the CS call can be either the MO call or the MT call. 
         [0057]    In step  304 , the method  300  includes sending a request to the manually selected CSG cell. The method  300  allows the controller module  204  to the UE  102  sends the request to the manually selected CSG cell  104   a . For example, the controller module  204  of the UE  102  sends an ESR to the manually selected CSG cell  104   a.    
         [0058]    In step  306 , the method  300  includes receiving the redirect request from the manually selected CSG cell  104   a . The method  300  allows the controller module  204  of the UE to  102  receive a redirect request from the manually selected CSG cell  104   a . The redirect request requests the UE  102  to camp on either a 3G cell or the 2G cell belonging to the PLMN  100   b , a different PLMN, or the RPLMN. 
         [0059]    In step  308 , the method  300  includes initiating the CSFB procedure to select the non-CSG cell. The method  300  allows the controller module  204  to the UE  102  initiates a CSFB procedure to select a non-CSG cell. Specifically, the controller module  204  of the UE  102  switches from the manually selected CSG cell  104   a  to a non-CSG cell, e.g., a macro cell, belonging to PLMN  100   b  or a different PLMN. In an example, the non-CSG cell can be a macro cell. 
         [0060]    In step  310 , the method  300  includes processing the CS call with the non-CSG cell. The method  300  allows the controller module  204  to UE  102  processes the CS call with the non-CSG cell. For example, the CS call can be processed at non-CSG cell  106   a  of PLMN  100   b . As another example, the CS call can be processed at non-CSG cell  106   b  or  106   c  of the PLMN  100   a  (i.e., the RPLMN). 
         [0061]    In step  312 , the UE  102  determines whether the CS call is ended. For example, the controller module  204  of the UE  102  determines whether the user has ended the CS call. 
         [0062]    If the CS call is ended, the UE  102  initiates a search to identify the manually selected CSG cell using pre-stored parameters in step  314 . Specifically, the controller module  204  of the UE  102  initiates the search to identify the manually selected CSG cell  104   a  using pre-stored parameters, e.g., the EARFCN, the CSG ID, and the cell ID. 
         [0063]    When the CS call is not ended, for the UE  102  continues processing the CS call with the non-CSG cell in step  310 . 
         [0064]    In step  316 , the UE  102  determines whether the manually selected CSG cell  104   a  is available. 
         [0065]    If the manually selected CSG cell  104   a  is available, the UE  102  camps on and registers with the manually selected CSG cell  104   a  in step  318 . The method  300  allows the controller module  204  to camp and register on the manually selected CSG cell  104   a . However, if the manually selected CSG cell  104   a  is unavailable, the UE  102  camps on and registers with the PLMN  100   a  (i.e., the RPLMN) using a stored duplicate value of the RPLMN. For example, the manually selected CSG cell  104   a  may be unavailable for the UE  102  when the UE  102  moves out of the coverage area of the manually selected CSG cell  104   a.    
         [0066]    The various steps illustrated in  FIG. 3  may be performed in the order presented, in a different order, simultaneously, or a combination thereof. Further, in some embodiments, some of the steps illustrated in the  FIG. 3  may be omitted. 
         [0067]      FIG. 4A  is a signal flow  400   a  diagram illustrating message signaling between a UE and PLMNs for processing an MO CS call while the UE is camped on a manually selected CSG cell, according to an embodiment of the present disclosure. Referring to  FIG. 4A , in step  402 , the UE  102  registers with the PLMN  100   a  (i.e., the RPLMN). 
         [0068]    In step  404 , the user  401  initiates a manual CSG selection on the PLMN  100   b , which is different from the RPLMN. 
         [0069]    In step  406 , the UE  102  sends a manual CSG selection request to the PLMN  100   b . Although not illustrated, in response to the manual CSG selection request from the UE  102 , the PLMN  100   b  sends the list of available CSG cells  104   a ,  104   b , and  104   c  to the UE  102 , which displays the list of available CSG cells to the user  401 . Thereafter, the user  401  selects a CSG cell from the list of available CSG cells. 
         [0070]    For example, in step  408 , when the user selects the CSG cell  104   a , the UE  102  registers with the user selected CSG cell  104   a  of the PLMN  100   b , which is different from the RPLMN, i.e., PLMN  100   a.    
         [0071]    In step  410 , the user  401  initiates a CS call on the UE  102 . 
         [0072]    In step  412 , the UE  102  detects the CS call initiated by the user  401  and sends an ESR to the manually selected CSG cell  104   a.    
         [0073]    In step  414 , in response to the ESR from the UE  102 , the manually selected CSG cell  104   a  of the PLMN  100   b  sends a redirect message to the UE  102 . The redirect message indicates that the UE  102  is to initiate a CSFB procedure in order to select a 3G/2G cell belonging to either the PLMN  100   b  or a different PLMN. For example, the UE  102  selects the non-CSG cell  106   a , e.g., a macro cell, on the PLMN  100   b , supports one or more services, e.g., GERA (2G) and UTRA (3G) services. 
         [0074]    In step  416 , the UE  102  processes the initiated CS call by selecting the non-CSG cell  106   a  on the PLMN  100   b.    
         [0075]      FIG. 4B  is a signal flow  400   b  diagram illustrating message signaling between a UE and PLMNs for camping on and registering with a manually selected CSG cell, after processing an MO CS, according to an embodiment of the present disclosure. 
         [0076]    Referring to FIG. B, the initiated CS call is processed by the UE  102  on the non-CSG cell belonging to the PLMN  100   b  or different PLMN through steps  402 - 416 , as illustrated in  FIG. 4A . 
         [0077]    When the initiated CS call is processed by the UE  102  or the initiated CS call is ended by the user  401  in step  418 , the UE  102  initiates a search for the manually selected CSG cell  104   a  on the PLMN  100   b  using the pre-stored parameters in step  420 . For example, the pre-stored parameters may include the EARFCN, the CSG ID, and the cell ID of the manually selected CSG cell  104   a.    
         [0078]    The UE  102  determines whether the manually selected CSG cell is available as a result of the search using the pre-stored parameters. 
         [0079]    If the manually selected CSG cell  104   a  is available, the UE  102  camps on and registers with the manually selected CSG cell  104   a  on PLMN  100   b  in step  422 . However, if the UE  102  determines that the manually selected CSG cell  104   a  is unavailable as a result of the search, then the UE  102  camps on and registers with the PLMN  100   a  (i.e., the RPLMN) using a stored duplicate value of the PLMN  100   a  in step  424 . 
         [0080]      FIG. 5A  is a signal flow  500   a  diagram illustrating message signaling between a UE and PLMNs for processing an MT CS call by a UE that is camped on a CSG cell, according to an embodiment of the present disclosure. 
         [0081]    Referring to  FIG. 5A , the UE  102  registers on the PLMN  100   a  (i.e., the RPLMN) in step  502 . 
         [0082]    In step  504 , the user  401  initiates a manual CSG selection on the PLMN  100   b , which is different from the RPLMN. 
         [0083]    In step  506 , the UE  102  sends a manual CSG selection request to the PLMN  100   b . Although not illustrated, in response to the manual CSG selection request from the UE  102 , the PLMN  100   b  sends a list of available CSG cells  104   a ,  104   b , and  104   c  to the UE  102 , which displays the list of the available CSG cells to the user  401 . Thereafter, the user selects one of the CSG cells from the list of the available CSG cells. 
         [0084]    For example, when the user selects the CSG cell  104   a , the UE  102  registers with the user selected CSG cell  104   a  on the PLMN  100   b  in step  508 . 
         [0085]    When an incoming CS call (an MT call) is made to the UE  102 , in step  510 , the UE  102  receives a paging message from the manually selected CSG cell  104   a , indicating the incoming CS call. 
         [0086]    In step  512 , the UE  102  sends an ESR to the manually selected CSG cell  104   a . In response to the ESR from the UE  102 , the manually selected CSG cell  104   a  sends a redirect message to the UE  102  in step  514 . The redirect message indicates that the UE  102  is to initiate a CSFB procedure in order to select a 3G/2G cell belonging to the PLMN  100   b  or a different PLMN. 
         [0087]    For example, when the UE  102  selects the non-CSG cell  106   a , e.g., a macro cell, of the PLMN  100   b , which supports one or more services, e.g., the GERA (2G) and the UTRA (3G) services, the UE  102  processes the initiated CS call by selecting the non-CSG cell  106   a  of the PLMN  100   b  in step  516 . 
         [0088]      FIG. 5B  is a signal flow  500   b  diagram illustrating message signaling between a UE and PLMNs for camping on and registering with a CSG cell, after processing an MT CS, according to an embodiment of the present disclosure. 
         [0089]    Referring to  FIG. 5B , the incoming CS call is processed by the UE  102  on a non-CSG cell of the PLMN  100   b  or a different PLMN through steps  502 - 516 , as illustrated in  FIG. 5A . 
         [0090]    When an incoming CS call is processed by the UE  102  or the incoming CS call is ended by the user  401  in step  518 , the UE  102  initiates a search for the manually selected CSG cell  104   a  on the PLMN  100   b  using the pre-stored parameters in step  520 . For example, the pre-stored parameters include the EARFCN, the CSG ID, and the cell ID of the manually selected CSG cell  104   a.    
         [0091]    The UE  102  determines whether the manually selected CSG cell is available as a result of the search with the pre-stored parameters. 
         [0092]    If the manually selected CSG cell  104   a  is available, then the UE  102  camps on and registers with the manually selected CSG cell  104   a  of the PLMN  100   b  in step  522 . However, if the UE  102  determines that the manually selected CSG cell  104   a  is unavailable as a result of the search, then the UE  102  camps on and registers with the PLMN  100   a  (i.e., the RPLMN) using a stored duplicate value of the PLMN  100   a  in step  524 . 
         [0093]    The embodiments described herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the elements of the embodiments. The elements illustrated in  FIGS. 1 ,  2 ,  4 A,  4 B,  5 A, and  5 B include blocks, which can be at least one of a hardware device, or a combination of hardware device and software module. 
         [0094]    Further, the various devices, modules, etc., as described herein, may be embodied as and operated using hardware circuitry, for example, complementary metal oxide semiconductor based logic circuitry, firmware, software and/or any combination of hardware, firmware, and/or software embodied in a machine readable medium. 
         [0095]    While the present disclosure has been particularly shown and described with reference to certain embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the following claims and their equivalents.