he mobility management entity (MME) to which the mobile is attached. Network Architecture It treats paging requests sent by the MME entity for their distribution in the cellphone corresponding to the radio coverage area of the eNB entity. The eNB entity also distributes system information to the cell containing the technical characteristics of the radio interface and allowing the mobile access to connect. The eNB entity uses the measurements made by the mobile to decide on the initiation of a cell change during a session (handover). 1.1.1.2. MME entity The MME entity is the network control tower, allowing mobile access and controlling bearer establishment for the transmission of traffic data. The MME entities belong to a group (pool). Load balancing of MME entities is provided by the eNB entities within a group that must have access to each MME entity of the same group. The MME entity is responsible for attachment and detachment of the mobile phone to the network concerned. During attachment, the MME entity retrieves the subscriber's profile and the subscriber's authentication data stored in the home subscriber server (HSS) and performs authentication of the mobile. During attachment, the MME entity registers the tracking area identity (TAI) of the mobile and allocates a globally unique temporary identity (GUTI) to the mobile which replaces the private international mobile subscriber identity (IMSI). The MME entity manages a list of location areas allocated to the mobile, where the mobile can move in an idle state, without contacting the MME entity to update its TAI location area. When attaching the mobile, the MME selects SGW and PGW (PDN Gateway) entities for the construction of the default bearer, e.g. for the transport of IP packets containing Session Initiation Protocol (SIP) signaling. VoLTE and ViLTE For the construction of the bearer, the selection of the PGW entity is obtained from the access point name (APN), communicated by the mobile or by the HSS entity in the subscriber's profile. The source MME ent