efault bearer, initiated by the mobile Source Message Destination PDN CONNECTIVITY REQUEST ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST or PDN CONNECTIVITY REJECT Establishment of dedicated bearer, initiated by the network Source Message Destination ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST ACTIVATE DEDICATED EPS BEARER CONTEXT ACCEPT or ACTIVATE DEDICATED EPS BEARER CONTEXT REJECT Modification of dedicated bearer, initiated by the network Source Message Destination MODIFY EPS BEARER CONTEXT REQUEST MODIFY EPS BEARER CONTEXT ACCEPT or MODIFY EPS BEARER CONTEXT REJECT 32 VoLTE and ViLTE Release of dedicated bearer, initiated by the network Source Message Destination DEACTIVATE EPS BEARER CONTEXT REQUEST DEACTIVATE EPS BEARER CONTEXT ACCEPT Establishment of dedicated bearer, initiated by the mobile Source Message Destination BEARER RESOURCE ALLOCATION REQUEST ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST or ACTIVATE DEDICATED EPS BEARER CONTEXT REJECT or MODIFY EPS BEARER CONTEXT REQUEST Modification of dedicated bearer, initiated by the mobile Source Message Destination BEARER RESOURCE MODIFICATION REQUEST ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST or MODIFY EPS BEARER CONTEXT REQUEST or DEACTIVATE EPS BEARER CONTEXT REQUEST or BEARER RESOURCE MODIFICATION REJECT Release of dedicated bearer, initiated by the mobile Source Message Destination PDN DISCONNECT REQUEST DEACTIVATE EPS BEARER CONTEXT REQUEST or PDN DISCONNECT REJECT Table 2.1. ESM messages 2.2. RRC protocol The RRC protocol is the signaling exchanged between the mobile and the evolved node base station (eNB) over the LTE-Uu radio interface. Signaling Protocols The RRC protocol performs the following functions: - broadcast of the system information related to the characteristics of the radio interface; - control of the RRC connection: this procedure includes the paging, the establishment, the modification and the release of the signaling radio bearer (SRB) and the data radio bearer (DRB). It also includes the activation of security mode over the LTE