Abstract:
Methods and apparatus, including computer program products, are provided for control of service. In one aspect there is provided a method. The method may include receiving, at an application client at the user equipment, access control information, wherein the access control information indicates whether access to a network is allowed; and determining, at the application client, whether to allow a call attempt by the user equipment based on at least the received access control information. Related apparatus, systems, methods, and articles are also described.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. §119(e) of the following provisional application, which is incorporated herein by reference in its entirety: U.S. Ser. No. 61/898,888, entitled “ENHANCED CONTROL OF SERVICES,” filed Nov. 1, 2013. 
    
    
     FIELD 
     The subject matter described herein relates to wireless communications. 
     BACKGROUND 
     Public land mobile networks may be configured to control access by user equipment. This access control may prevent certain user equipment from initiating access to the network, responding to network pages, and the like. For example, in an emergency, a network service provider may control access in order to reduce network congestion. The base station serving a cell may broadcast information to user equipment, and this broadcast may indicate the types of user equipment barred access to the network. Specifically, a user equipment may be assigned to an access class (AC), such as 0 to 9. The assigned access class may be stored in the user equipment in a subscriber identity module (SIM), universal SIM, and/or any other secure storage mechanism. A user equipment may also be assigned to certain high priority access classes, such as access classes  11  to  15 , which can also be stored in the SIM, USIM, and the like, and calls made as emergency calls are handled as access class  10 . 
     When congestion or a network overload condition occurs, such as during an emergency, the network may broadcast which access classes are access barred, the duration of the barring, and/or the rate of the barring. The user equipment may receive the indication and then not allow accessing to the network, responding to a page, and/or the like. 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Service accessibility (Release 12), 3GPP TS 22.011, V12.0.0 (2013-03) (hereinafter TS 22.011) provides an example of a specification for access barring. 
     SUMMARY 
     Methods and apparatus, including computer program products, are provided for control of service. 
     In some example embodiments, there is provided a method The method may include receiving, at an application client at the user equipment, access control information, wherein the access control information indicates whether access to a network is allowed; and determining, at the application client, whether to allow a call attempt by the user equipment based on at least the received access control information. 
     In some variations, one or more of the features disclosed herein including the following features can optionally be included in any feasible combination. The access control information may be provided to the application client by an access stratum. The access control information may include emergency access barring. The call attempt may include an emergency call attempt. The emergency call attempt may include one of the multimedia telephone voice for emergency call or circuit switch fall back emergency call. The application client may allow the emergency call attempt, when the access control information for the emergency call attempt is not available. The application client may allow emergency call attempt, when the access control information for the emergency call allows the emergency call attempt. The application client may bar the emergency call attempt, when the access control information for the emergency call is not available. An access class of the user equipment may be accessed to determine whether access to the network is barred. The application client may include at least one of an internet protocol multimedia subsystem client and a session initiation protocol client. The access control information may be retrieved from an access stratum comprising a radio resource control client at the user equipment. The radio resource control client may receive the access control information from a base station via at least one of a system information and a dedicated signaling, wherein the access control information includes one or more access barring parameters. The call attempt may include at least one of a voice over long term evolution call, a multimedia telephony call, and a multimedia video call, a data call, a high-priority call, and a signaling exchange. The access control information may include at least one of access class barring information and a service specific access control information. The application client may allow, based on the determining, the call attempt, when the received access barring information indicates access is not access barred. The user equipment may be in a radio resource control idle state. The user equipment may be in a radio resource control connected state. 
     The above-noted aspects and features may be implemented in systems, apparatus, methods, and/or articles depending on the desired configuration. The details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       In the drawings, 
         FIG. 1  depicts an example of a system for access barring, in accordance with some exemplary embodiments; 
         FIG. 2  depicts an example of a process for access barring, in accordance with some exemplary embodiments; 
         FIG. 3  depicts another example of a system in which access barring may be practiced, in accordance with some exemplary embodiments; 
         FIG. 4  depicts an example of an apparatus, in accordance with some exemplary embodiments; and 
         FIG. 5  depicts an example of a network node, in accordance with some exemplary embodiments. 
     
    
    
     Like labels are used to refer to same or similar items in the drawings. 
     DETAILED DESCRIPTION 
     Due in part to the proliferation of user equipment including smartphones, land mobile network operators are experiencing increases in signaling and traffic loads on their networks. This load increase becomes somewhat of a problem during certain events, such as disasters, riots, public concerts, sporting events, and other mass events. Specifically, an event can trigger a mass of user-generated and/or application-generated accesses to the network concentrated within a certain time, causing severe congestion in the network including the radio access network and core networks. 
     Given the possibility of congestion, a mobile network operator may want to prioritize certain services and/or accesses to the network. For example, emergency access and high priority access to the network may be given priority over other accesses. In addition or alternatively, priority may be given to certain signaling messages, such as radio resource control (RRC)/network access stratum (NAS) messages over normal traffic or other types of signaling. In addition or alternatively, priority may be given to certain types of services, such as voice services over non-voice services (or vice versa). The control of the prioritization control may be mobile network operator-specific, depending thus on specific policies at the mobile network operator. For example, a mobile network operator may want to configure access barring, so that user equipment is allowed to make emergency calls but preventing the user equipment from initiating other types of accesses (of vice versa). 
     3GPP TS 22.011 does provide some uplink congestion mitigation control mechanisms. For example, a Service Specific Access Control (SSAC) congestion control mechanism may be implemented, so that the network can suppress, when congestion occurs, initiation of multimedia telephony (MMTEL-voice) and multimedia telephony vide (MMTEL-video). However, SSAC does not work for prioritizing MMTEL-voice over normal data. Access Class Barring (ACB) congestion control mechanism may be implemented, so that the network can control, during times of congestion, connection requests (for example, mobile originated (MO)-data and MO-signaling). But voice services are considered MO-data in ACB, so applying ACB results in voice services being suppressed along with non-voice services. RRC Connection Reject signaling provides a congestion control mechanism as well. RRC Connection Reject allows the network to reject connection requests based on establishment cause (for example, MO-data in congestion). However, the base station/eNB cannot typically recognize connection requests aiming for voice, so the base station/eNB would reject voice service requests in congestion. Lastly, Random Access (RA) Backoff provides a congestion control mechanism that allows the network to delay random access attempts in congestion. However, applying RA backoff may result in voice service initiations being delayed along with non-voice services. Thus, although some specifications provide uplink congestion mitigation mechanisms, mobile network operators may not be able to rely on past mechanisms for the purpose of prioritizing or prevention of mobile originating voice calls in congestion. 
     In some example embodiments, the subject matter disclosed herein relates to connected mode, such as radio resource control (RRC) connected mode, operation with respect to emergency calls and access class barring (ACB). 
     In some example embodiments, voice calls, such as voice over long term evolution (VoLTE) calls, are considered access class barring (ACB) and emergency barring in a cell. However, to avoid double barring, the access class barring may only be applied at an internet protocol multimedia system (IMS) level, bypassing thus ACB at the access stratum level. In effect, ACB/emergency barring is applied at the IMS level (for example, at a session initiation protocol (SIP) proxy, an application, and/or the like), rather than at a lower-level access stratum level, such as part of RRC connection establishment. However, double barring may be applied as well, so that normal ACB is applied at the access stratum (AS, i.e., radio layer), and ACB plus SSAC/emergency barring is applied at the IMS level. 
       FIG. 1A  depicts an example system  100  for enhanced control of services, in accordance with some example embodiments. 
     The system  100  may include at least one user equipment  114 A and a network including a base station  110 A. The user equipment  114 A may further include a SIM  116 , which further includes an access class for the SIM and the corresponding user equipment  114 A. The user equipment  114 A may further include an IMS client  118  for IMS services  118  (including, for example, a SIP client, an application client, an IP client, and the like). The user equipment may also have system information acquired on the AS layer (for example, acquired from a broadcast channel) including access barring information  120  provided by the network  110 A. 
     In some example embodiments, the access stratum (AS) may inform the IMS layer about access class barring of a certain type of access or service. The ACB and emergency barring information is provided from the AS layer to the IMS layer, such as IMS client  118 , to enable the barring. As such, access class barring (ACB) may, in some example embodiments, be checked on the IMS layer, such as by the IMS client  118 . 
     Base station  110 A may provide an access barring information via a broadcast, a system information block (SIB), and/or other signaling. For example, the access barring information may indicated access class  10  (emergency calls) is access barred. When an emergency call is initiated, IMS client  118  may perform, in accordance with some example embodiments, a check to see whether the emergency call is access barred, and, if so, IMS client  118  may bar the emergency call without initiating a call establishment on the AS layer where the allowance of emergence access may be checked again. 
     Additionally or alternatively, access barring may be applied when the user equipment is in a connected mode. During an active connection, base station  110 A may send access barring parameters in a system information block and the like. The IMS client  118  may receive the access barring parameters and determine, in accordance with some example embodiments, whether the active connection has been access barred by the network. 
     The IMS client  118  may receive from a lower layer (for example, from the access stratum (AS) layer) access barring information  120 . Table 1 below depicts an example of access barring information, in accordance with some example embodiments. The access barring information at Table 1 may be sent to user equipment  114 A, where it can be retrieved by the IMS client  118 . The IMS client at the user equipment may be provided with access barring information that bars, for example, some if not all MMTEL during an emergency. In addition or alternatively, ACB information may be defined for MMTEL in similar way as is done with CSFB. Specifically, a system information block may include barring information for mobile originated CSFB calls and MMTEL calls (for example, IMS voice calls). 
     The following provides an example behavior for an MMTEL call, so that an additional check at the IMS client  118  is added to enable access barring checks for emergency call handling (for example, ac-BarringInfo at Table 1). 
     
       
         
               
             
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Service Specific Access Control 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 BarringFactorForMMTEL-Voice: barring rate for MMTEL voice; 
               
               
                 BarringTimeForMMTEL-Voice: barring timer for MMTEL voice; 
               
               
                 BarringFactorForMMTEL-Video: barring rate for MMTEL video; and 
               
               
                 BarringTimeForMMTEL-Video: barring timer for MMTEL video. 
               
               
                 ac-BarringInfo completely or barring for just some portions, such as 
               
               
                 ac-BarringForEmergency. 
               
               
                   
               
             
          
         
       
     
       FIG. 2  depicts an example process for access barring, in accordance with some example embodiments. The description of process  200  also refers to  FIG. 1 . 
     When a request to establish a call, such as a multimedia telephony (MMTEL) communications session and the like, is received, user equipment  114 A including IMS client  118  may, at  205 , determine whether the multimedia telephony communications session is to be established as an emergency session. If not (no at  205  and  207 ), the user equipment  114 /IMS client  118  may allow session establish to continue in accordance with access class bearing (ACB) and service specific access control (SSAC) procedures (as described for example in 3GPP TS 24.173, sub clause 2.) 
     If so (yes at  205  and  209 ), the IMS client  118  may retrieve from a lower access stratum layer one or more access barring parameters including access barring for emergency parameter (for example, ac-BarringForEmergency parameter at Table 1). This access barring for emergency parameter may be provided by the network to the user equipment. 
     If the access barring for emergency parameter (for example, ac-BarringForEmergency) is not available, the IMS client  118  may allow the emergency call to continue (no at  209  and  211 ). 
     If the access barring for emergency parameter (for example, ac-BarringForEmergency) is available and the access barring for emergency parameter is true (for example, ac-BarringForEmergency indicates emergency calls being access barred), the IMS client  118  may reject the emergency call (yes at  213  and  217 ). 
     If the access barring for emergency parameter (for example, ac-BarringForEmergency) is available and the access barring for emergency parameter is false (for example, ac-BarringForEmergency indicates emergency calls not being access barred), the IMS client  118  may allow the emergency call to continue (no at  213  and  215 ). Alternatively, If the access barring for emergency parameter (for example, ac-BarringForEmergency) is not available, it can be specified that the emergency call is not allowed. 
     Tables 2 and 3 below depicts an example specification for the process  200 . 
     
       
         
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
             
             
               
                 1) 
                 if the multimedia telephony communication session to be established 
               
               
                   
                  is an emergency session, then skip the rest of steps below and 
               
               
                   
                  continue with session establishment as described in subclause 5.2, 
               
               
                   
                  unless the ac-BarringForEmergency is set to TRUE; 
               
             
          
           
               
                   
                 a. 
                 retrieve SSAC related information mentioned above from lower 
               
               
                   
                   
                  layers 
               
               
                   
                 b. 
                 if the user equipment has one or more Access Classes, as 
               
               
                   
                   
                  stored on the USIM, with a value in the range 11..15, 
               
               
                   
                   
                  which is valid for the user equipment to use according 
               
               
                   
                   
                  to TS 22.011 [10] and TS 23.122 [11]: 
               
             
          
           
               
                   
                 i. 
                 if the ac-BarringInfo includes ac-BarringForMO-Data, 
               
               
                   
                   
                   and for all of these valid Access Classes for the 
               
               
                   
                   
                   user equipment, the corresponding bit in the  
               
               
                   
                   
                  ac-BarringForSpecialAC contained in  
               
               
                   
                   
                  ac- BarringForMO-Data is set to one: 
               
             
          
           
               
                   
                 1. 
                 reject the multimedia telephony communication session 
               
               
                   
                   
                  establishment; 
               
             
          
           
               
                   
                 c. 
                 else: 
               
             
          
           
               
                   
                 i. 
                 reject the multimedia telephony communication session 
               
               
                   
                   
                  establishment; 
               
             
          
           
               
                 2) 
                 retrieve SSAC related information mentioned above from 
               
               
                   
                  lower layers. 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
             
               
               
             
               
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
             
             
               
                   
                 Upon request from the upper layers, the user equipment shall: 
               
             
          
           
               
                 1&gt; 
                 set the local variables BarringFactorForMMTEL-Voice and BarringTimeForMMTEL-Voice as 
               
               
                   
                 follows: 
               
             
          
           
               
                   
                 2&gt; 
                 if the user equipment is in RRC_IDLE and ssac-BarringForMMTEL-Voice is present: 
               
             
          
           
               
                   
                 3&gt; 
                 if the user equipment has one or more Access Classes, as stored on the USIM, with a 
               
               
                   
                   
                 value in the range 11..15, which is valid for the user equipment to use according to TS 
               
               
                   
                   
                 22.011 [10] and TS 23.122 [11], and 
               
             
          
           
               
                 NOTE: 
                 ACs 12, 13, 14 are only valid for use in the home country and ACs 11, 15 are only valid 
               
               
                   
                 for use in the HPLMN/ EHPLMN. 
               
             
          
           
               
                   
                 3&gt; 
                 if, for at least one of these Access Classes, the corresponding bit in the ac- 
               
               
                   
                   
                 BarringForSpecialAC contained in ssac-BarringForMMTEL-Voice is set to zero: 
               
             
          
           
               
                   
                 4&gt; 
                 set BarringFactorForMMTEL-Voice to one and BarringTimeForMMTEL-Voice to 
               
               
                   
                   
                 zero; 
               
             
          
           
               
                   
                 3&gt; 
                 else: 
               
             
          
           
               
                   
                 4&gt; 
                 set BarringFactorForMMTEL-Voice and BarringTimeForMMTEL-Voice to the value 
               
               
                   
                   
                 of ac-BarringFactor and ac-BarringTime included in ssac-BarringForMMTEL-Voice, 
               
               
                   
                   
                 respectively; 
               
             
          
           
               
                   
                 2&gt; 
                 else set BarringFactorForMMTEL-Voice to one and BarringTimeForMMTEL-Voice to zero; 
               
             
          
           
               
                 1&gt; 
                 set the local variables BarringFactorForMMTEL-Video and BarringTimeForMMTEL-Video as 
               
               
                   
                 follows: 
               
             
          
           
               
                   
                 2&gt; 
                 if the user equipment is in RRC_IDLE and ssac-BarringForMMTEL-Video is present: 
               
             
          
           
               
                   
                 3&gt; 
                 if the user equipment has one or more Access Classes, as stored on the USIM, with a 
               
               
                   
                   
                 value in the range 11..15, which is valid for the user equipment to use according to TS 
               
               
                   
                   
                 22.011 [10] and TS 23.122 [11], and 
               
               
                   
                 3&gt; 
                 if, for at least one of these Access Classes, the corresponding bit in the ac- 
               
               
                   
                   
                 BarringForSpecialAC contained in ssac-BarringForMMTEL-Video is set to zero: 
               
             
          
           
               
                   
                 4&gt; 
                 set BarringFactorForMMTEL-Video to one and BarringTimeForMMTEL-Video to 
               
               
                   
                   
                 zero; 
               
             
          
           
               
                   
                 3&gt; 
                 else: 
               
             
          
           
               
                   
                 4&gt; 
                 set BarringFactorForMMTEL-Video and BarringTimeForMMTEL-Video to the value 
               
               
                   
                   
                 of ac-BarringFactor and ac-BarringTime included in ssac-BarringForMMTEL-Video, 
               
               
                   
                   
                 respectively; 
               
             
          
           
               
                   
                 2&gt; 
                 else set BarringFactorForMMTEL-Video to one and BarringTimeForMMTEL-Video to zero; 
               
             
          
           
               
                 1&gt; 
                 forward the variables BarringFactorForMMTEL-Voice, BarringTimeForMMTEL-Voice, 
               
               
                   
                 BarringFactorForMMTEL-Video and BarringTimeForMMTEL-Video, ac-BarringInfo to the 
               
               
                   
                 upper layers; 
               
               
                   
               
             
          
         
       
     
     Although the previous example describes the IMS client retrieving the access barring for emergency parameter, other access barring parameters may be retrieved by the IMS client to bar certain calls at the IMS layer as well. 
     In the case of access class barring non-emergency calls, the access class barring may be made independent of SSAC (for example, if SSAC allows access then access class barring may block it). If both SSAC and ACB do not deny access at the IMS client  118 , then the call is allowed. Table 4 below depicts an example specification for this second case. Third, if both SSAC and/or access class barring deny access and blocked at IMS client level, access class barring need not be checked at access stratum level. 
     
       
         
               
               
             
               
               
               
             
               
               
               
             
               
               
             
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
             
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
             
             
               
                 3) 
                 if video is offered in the multimedia telephony communication session: 
               
             
          
           
               
                   
                 A) 
                 if back-off timer Tx is running, reject the multimedia telephony communication session 
               
               
                   
                   
                 establishment and skip the rest of steps below; or 
               
               
                   
                 B) 
                 else, then: 
               
             
          
           
               
                   
                 I) 
                 draw a new random number “rand1” that is uniformly distributed in the range 0 ≦ rand1 
               
               
                   
                   
                 &lt; 1; and 
               
               
                   
                 II) 
                 if the random number “rand1” is lower than BarringFactorForMMTEL-Video, then skip 
               
               
                   
                   
                 the rest of steps below and continue with session establishment as described in 
               
               
                   
                   
                 subclause 5.2; OR 
               
               
                   
                 II.A) 
                 if ac-BarringInfo provided by lower layers; 
               
             
          
           
               
                   
                 if the user equipment has one or more Access Classes, as stored on the USIM, with a 
               
             
          
           
               
                   
                 value in the range 11..15, which is valid for the user equipment to use according to 
               
               
                   
                 TS 22.011 [10] and TS 23.122 [11], and for at least one of these valid Access 
               
               
                   
                 Classes the corresponding bit in the ac-BarringForSpecialAC contained in “AC 
               
               
                   
                 barring parameter” is set to zero then skip the rest of steps below and continue with 
               
               
                   
                 session establishment as described in subclause 5.2; 
               
             
          
           
               
                   
                 i) 
                 for at least one of these valid Access Classes the corresponding bit in the ac- 
               
               
                   
                   
                 BarringForSpecialAC contained in “AC barring parameter” is set to zero: 
               
             
          
           
               
                   
                 a) 
                 then skip the rest of steps below and continue with session establishment as 
               
               
                   
                   
                 described in subclause 5.2; 
               
             
          
           
               
                   
                 ii) 
                 else: 
               
             
          
           
               
                   
                 a) 
                 draw a random number ‘rand’ uniformly distributed in the range: 0 ≦ rand &lt; 1; 
               
               
                   
                 b) 
                 if ‘rand’ is lower than the value indicated by ac-BarringFactor included in “AC 
               
               
                   
                   
                 barring parameter”: 
               
             
          
           
               
                   
                 1) 
                 then skip the rest of steps below and continue with session establishment as 
               
               
                   
                   
                 described in subclause 5.2; 
               
             
          
           
               
                   
                 c) 
                 else: 
               
             
          
           
               
                   
                 1) 
                 reject the multimedia telephony communication session establishment; 
               
             
          
           
               
                   
                 III) else, then; 
               
             
          
           
               
                   
                 i) 
                 draw a new random number “rand2” that is uniformly distributed in the range 0 ≦ 
               
               
                   
                   
                 rand2 &lt; 1; and 
               
               
                   
                 ii) 
                 start back-off timer Tx with the timer value calculated using the formula: 
               
             
          
           
               
                   
                 Tx = (0,7 + 0,6*rand2) * BarringTimeForMMTEL-Video; and 
               
             
          
           
               
                   
                 iii) 
                 reject the multimedia telephony communication session establishment and skip the 
               
               
                   
                   
                 rest of steps below; 
               
             
          
           
               
                 4) 
                 if audio is offered in the multimedia telephony communication session: 
               
             
          
           
               
                   
                 A) 
                 if back-off timer Ty is running, reject the multimedia telephony communication session 
               
               
                   
                   
                 establishment and skip the rest of steps below; or 
               
               
                   
                 B) 
                 else, then; 
               
             
          
           
               
                   
                 I) 
                 draw a new random number “rand3” that is uniformly distributed in the range 0 ≦ rand3 
               
               
                   
                   
                 &lt; 1; and 
               
               
                   
                 II) 
                 if the random number “rand3” is lower than BarringFactorForMMTEL-Voice, then skip 
               
               
                   
                   
                 the rest of steps below and continue with session establishment as described in 
               
               
                   
                   
                 subclause 5.2; OR 
               
               
                   
                 II.A) 
                 if ac-BarringInfo provided by lower layers; 
               
             
          
           
               
                   
                 if the user equipment has one or more Access Classes, as stored on the USIM, with a 
               
             
          
           
               
                   
                   
                 value in the range 11..15, which is valid for the user equipment to use according to 
               
               
                   
                   
                 TS 22.011 [10] and TS 23.122 [11], and for at least one of these valid Access 
               
               
                   
                   
                 Classes the corresponding bit in the ac-BarringForSpecialAC contained in “AC 
               
               
                   
                   
                 barring parameter” is set to zero then skip the rest of steps below and continue with 
               
               
                   
                   
                 session establishment as described in subclause 5.2; 
               
               
                   
                 i) 
                 for at least one of these valid Access Classes the corresponding bit in the ac- 
               
               
                   
                   
                 BarringForSpecialAC contained in “AC barring parameter” is set to zero: 
               
             
          
           
               
                   
                 a) 
                 then skip the rest of steps below and continue with session establishment as 
               
               
                   
                   
                 described in subclause 5.2; 
               
             
          
           
               
                   
                 ii) 
                 else: 
               
             
          
           
               
                   
                 a) 
                 draw a random number ‘rand’ uniformly distributed in the range: 0 ≦ rand &lt; 1; 
               
               
                   
                 b) 
                 if ‘rand’ is lower than the value indicated by ac-BarringFactor included in “AC 
               
               
                   
                   
                 barring parameter”: 
               
             
          
           
               
                   
                 1) 
                 then skip the rest of steps below and continue with session establishment as 
               
               
                   
                   
                 described in subclause 5.2; 
               
             
          
           
               
                   
                 c) 
                 else: 
               
             
          
           
               
                   
                 1) 
                 reject the multimedia telephony communication session establishment; 
               
             
          
           
               
                   
                 III) else, then; 
               
             
          
           
               
                   
                 i) 
                 draw a new random number “rand4” that is uniformly distributed in the range 0 ≦ 
               
               
                   
                   
                 rand4 &lt; 1; and 
               
               
                   
                 ii) 
                 start timer Ty with the timer value calculated using the formula: 
               
             
          
           
               
                   
                 Ty = (0,7 + 0,6*rand4) * BarringTimeForMMTEL-Voice; and 
               
             
          
           
               
                   
                 iii) 
                 reject the multimedia telephony communication session establishment; 
               
               
                   
               
             
          
         
       
     
       FIG. 3  depicts system  100  with additional detail with respect to the network. Referring to  FIG. 1 , the system  100  may include one or more user equipment  114 A-B coupling wirelessly to one or more base stations, such as base stations  110 A-C (labeled eNB, evolved Node B). The system  100  may further includes other nodes, such as a mobility management entity (MME), a serving gateway (SGW), and/or a packet gateway (PGW)  172 A-B. The system  100  may also include one or more application servers, such as application server  180 . Although  FIG. 1  depicts an E-UTRAN (Evolved Uniform Mobile Telecommunications System Terrestrial Radio Access Network), other frameworks may be used as well. In the case of E-UTRAN, eNB base stations may provide an E-UTRA (Evolved Universal Terrestrial Radio Access) user plane and control plane protocol terminations towards the user equipment. The eNB base stations may be interconnected with each other by means of an X2 interface. The eNB base stations may also be connected via an S1 interface to an Evolved Packet Core (EPC) including other nodes, such as a mobility management entity (MME), a serving gateway (SGW), and/or a packet gateway (PGW). 
       FIG. 4  illustrates a block diagram of an apparatus  10 , which can be configured as user equipment  114 A. Apparatus  10  may be implemented as a smart phone, mobile station, a mobile unit, a subscriber station, a wireless terminal, a tablet, a wireless plug-in accessory, or any other device with a short-range transceiver, such as Bluetooth, Bluetooth Low Energy, and the like. In some example embodiments, one or more portions of the apparatus  10  may be incorporated into a media player, such as a television, wireless speaker, and the like. 
     The apparatus  10  may include at least one antenna  12  in communication with a transmitter  14  and a receiver  16 . Alternatively transmit and receive antennas may be separate. 
     The apparatus  10  may also include a processor  20  configured to provide signals to and receive signals from the transmitter and receiver, respectively, and to control the functioning of the apparatus. Processor  20  may be configured to control the functioning of the transmitter and receiver by effecting control signaling via electrical leads to the transmitter and receiver. Likewise, processor  20  may be configured to control other elements of apparatus  10  by effecting control signaling via electrical leads connecting processor  20  to the other elements, such as a display or a memory. The processor  20  may, for example, be embodied in a variety of ways including circuitry, at least one processing core, one or more microprocessors with accompanying digital signal processor(s), one or more processor(s) without an accompanying digital signal processor, one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuitry, one or more computers, various other processing elements including integrated circuits (for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), and/or the like), or some combination thereof. Accordingly, although illustrated in  FIG. 4  as a single processor, in some example embodiments the processor  20  may comprise a plurality of processors or processing cores. 
     Signals sent and received by the processor  20  may include signaling information in accordance with an air interface standard of an applicable cellular system, and/or any number of different wireline or wireless networking techniques, comprising but not limited to Wi-Fi, wireless local access network (WLAN) techniques, such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, 802.16, and/or the like. In addition, these signals may include speech data, user generated data, user requested data, and/or the like. 
     The apparatus  10  may be capable of operating with one or more air interface standards, communication protocols, modulation types, access types, and/or the like. For example, the apparatus  10  and/or a cellular modem therein may be capable of operating in accordance with various first generation (1G) communication protocols, second generation (2G or 2.5G) communication protocols, third-generation (3G) communication protocols, fourth-generation (4G) communication protocols, Internet Protocol Multimedia Subsystem (IMS) communication protocols (for example, session initiation protocol (SIP) and/or the like. For example, the apparatus  10  may be capable of operating in accordance with 2G wireless communication protocols IS-136, Time Division Multiple Access TDMA, Global System for Mobile communications, GSM, IS-95, Code Division Multiple Access, CDMA, and/or the like. In addition, for example, the apparatus  10  may be capable of operating in accordance with 2.5G wireless communication protocols General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), and/or the like. Further, for example, the apparatus  10  may be capable of operating in accordance with 3G wireless communication protocols, such as Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access 2000 (CDMA2000), Wideband Code Division Multiple Access (WCDMA), Time Division-Synchronous Code Division Multiple Access (TD-SCDMA), and/or the like. The apparatus  10  may be additionally capable of operating in accordance with 3.9G wireless communication protocols, such as Long Term Evolution (LTE), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and/or the like. Additionally, for example, the apparatus  10  may be capable of operating in accordance with 4G wireless communication protocols, such as LTE Advanced and/or the like as well as similar wireless communication protocols that may be subsequently developed. 
     It is understood that the processor  20  may include circuitry for implementing audio/video and logic functions of apparatus  10 . For example, the processor  20  may comprise a digital signal processor device, a microprocessor device, an analog-to-digital converter, a digital-to-analog converter, and/or the like. Control and signal processing functions of the apparatus  10  may be allocated between these devices according to their respective capabilities. The processor  20  may additionally comprise an internal voice coder (VC)  20   a , an internal data modem (DM)  20   b , and/or the like. Further, the processor  20  may include functionality to operate one or more software programs, which may be stored in memory. In general, processor  20  and stored software instructions may be configured to cause apparatus  10  to perform actions. For example, processor  20  may be capable of operating a connectivity program, such as a web browser. The connectivity program may allow the apparatus  10  to transmit and receive web content, such as location-based content, according to a protocol, such as wireless application protocol, WAP, hypertext transfer protocol, HTTP, and/or the like. 
     Apparatus  10  may also comprise a user interface including, for example, an earphone or speaker  24 , a ringer  22 , a microphone  26 , a display  28 , a user input interface, and/or the like, which may be operationally coupled to the processor  20 . The display  28  may, as noted above, include a touch sensitive display, where a user may touch and/or gesture to make selections, enter values, and/or the like. The processor  20  may also include user interface circuitry configured to control at least some functions of one or more elements of the user interface, such as the speaker  24 , the ringer  22 , the microphone  26 , the display  28 , and/or the like. The processor  20  and/or user interface circuitry comprising the processor  20  may be configured to control one or more functions of one or more elements of the user interface through computer program instructions, for example, software and/or firmware, stored on a memory accessible to the processor  20 , for example, volatile memory  40 , non-volatile memory  42 , and/or the like. The apparatus  10  may include a battery for powering various circuits related to the mobile terminal, for example, a circuit to provide mechanical vibration as a detectable output. The user input interface may comprise devices allowing the apparatus  20  to receive data, such as a keypad  30  (which can be a virtual keyboard presented on display  28  or an externally coupled keyboard) and/or other input devices. 
     As shown in  FIG. 4 , apparatus  10  may also include one or more mechanisms for sharing and/or obtaining data. For example, the apparatus  10  may include a short-range radio frequency (RF) transceiver and/or interrogator  64 , so data may be shared with and/or obtained from electronic devices in accordance with RF techniques. The apparatus  10  may include other short-range transceivers, such as an infrared (IR) transceiver  66 , a Bluetooth (BT) transceiver  68  operating using Bluetooth wireless technology, a wireless universal serial bus (USB) transceiver  70 , a Bluetooth Low Energy link, ZigBee link, a cellular device-to-device link, a wireless local area link, a Wi-Fi link, and/or any other short-range radio technology. In this regard, the apparatus  10  and, in particular, the short-range transceiver may be capable of transmitting data to and/or receiving data from electronic devices within the proximity of the apparatus, such as within 10 meters, for example. The apparatus  10  including the WiFi or wireless local area networking modem may also be capable of transmitting and/or receiving data from electronic devices according to various wireless networking techniques, including 6LoWpan, Wi-Fi, Wi-Fi low power, WLAN techniques such as IEEE 802.11 techniques, IEEE 802.15 techniques, IEEE 802.16 techniques, and/or the like. 
     The apparatus  10  may comprise memory, such as a subscriber identity module (SIM)  38 , a removable user identity module (R-UIM), an eUICC, an UICC, and/or the like, which may store information elements related to a mobile subscriber. In addition to the SIM, the apparatus  10  may include other removable and/or fixed memory. The apparatus  10  may include volatile memory  40  and/or non-volatile memory  42 . For example, volatile memory  40  may include Random Access Memory (RAM) including dynamic and/or static RAM, on-chip or off-chip cache memory, and/or the like. Non-volatile memory  42 , which may be embedded and/or removable, may include, for example, read-only memory, flash memory, magnetic storage devices, for example, hard disks, floppy disk drives, magnetic tape, optical disc drives and/or media, non-volatile random access memory (NVRAM), and/or the like. Like volatile memory  40 , non-volatile memory  42  may include a cache area for temporary storage of data. At least part of the volatile and/or non-volatile memory may be embedded in processor  20 . The memories may store one or more software programs, instructions, pieces of information, data, and/or the like which may be used by the apparatus for performing functions of the user equipment/mobile terminal. The memories may comprise an identifier, such as an international mobile equipment identification (IMEI) code, capable of uniquely identifying apparatus  10 . The memories may comprise an identifier, such as an international mobile equipment identification (IMEI) code, capable of uniquely identifying apparatus  10 . In the example embodiment, the processor  20  may be configured using computer code stored at memory  40  and/or  42  to cause one or more of the operations disclosed herein with respect to the user equipment including process  200 , receiving access barring parameters, access barring at the IMS level certain calls, and the like as disclosed herein. 
       FIG. 5  depicts an example implementation of a network node  500 , such as for example a base station, an access point, and the like. The network node  500  may include one or more antennas  520  configured to transmit via a downlink and configured to receive uplinks via the antenna(s)  520 . The network node  500  may further include a plurality of radio interfaces  540  coupled to the antenna  520 . The radio interfaces may correspond one or more of the following: Long Term Evolution (LTE, or E-UTRAN), Third Generation (3G, UTRAN, or high speed packet access (HSPA)), Global System for Mobile communications (GSM), wireless local area network (WLAN) technology, such as for example 802.11 WiFi and/or the like, Bluetooth, Bluetooth low energy (BT-LE), near field communications (NFC), and any other radio technologies. The radio interface  540  may further include other components, such as for example filters, converters (for example, digital-to-analog converters and the like), mappers, a Fast Fourier Transform (FFT) module, and the like, to generate symbols for a transmission via one or more downlinks and to receive symbols (for example, via an uplink). The network node  500  may further include one or more processors, such as for example processor  530 , for controlling the network node  500  and for accessing and executing program code stored in memory  535 . In some example embodiments, memory  535  includes code, which when executed by at least one processor causes one or more of the operations described herein with respect to network node, such as for example a base station, access point, and the like. For example, network node  500  may send access barring parameters to the user equipment and/or perform other operations associated with the network node, base station, or access points disclosed herein. 
     Some of the embodiments disclosed herein may be implemented in software, hardware, application logic, or a combination of software, hardware, and application logic. The software, application logic, and/or hardware may reside on memory  40 , the control apparatus  20 , or electronic components, for example. In some example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a “computer-readable medium” may be any non-transitory media that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer or data processor circuitry, with examples depicted at  FIGS. 4 and 5 . A computer-readable medium may comprise a non-transitory computer-readable storage medium that may be any media that can contain or store the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. In addition, some of the embodiments disclosed herein include computer programs configured to cause methods as disclosed herein. 
     Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect of one or more of the example embodiments disclosed herein is enhanced control of emergency calls. 
     If desired, the different functions discussed herein may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined. Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims. It is also noted herein that while the above describes example embodiments, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications that may be made without departing from the scope of the present invention as defined in the appended claims. Other embodiments may be within the scope of the following claims. The term “based on” includes “based on at least.”