5G AMF – Access and Mobility Management Function

As per 3GPP 5G Network Architecture  an AMF is a 5G Core Network network function. AMF full name is Access and Mobility Management Function. Its primary tasks are similar to 4G MME which include Registration Management, Connection Management, Reachability Management, Mobility Management and various function relating to security and access management and authorization.

AMF Interfaces

AMF is the center node which interacts with the mostly all Control Plane Function like SMF, AUSF, UDM etc. Considering Reference-Point Architecture following are the major interface a AMF can have listed below and shown figure .

  • N2 interface connects 5G RAN with AMF
  • N8 interface connects AMF with UDM
  • N11 interface connects AMF with SMF
  • N12 inteface connects AMF with AUSF
  • N14 interface connects AMF with another AMF
  • N15 interface connects AMF with PCF
  • N22 interface connects AMF with NSSF (Network Slice Selection Function)
  • N26 interface connects AMF with 4G MME

AMF Functions and Responsibilities

  • AMF is a corntrol plane network function and its primary responsibilities include, Registration Management, Connection Management and Mobility Management
  • AMF is also responsible for NGAP signalling between the AMF and gNB. NGAP signalling procedures include PDU Session Management,  Paging, Configuration Transfer, UE Context Management, Transport of NAS Messages, Warning MessageUE Mobility Management Interface Management Transmission
  • AMF is responsible for selecting an appropriate Authentication Server Function (AUSF), Unified Data Management (UDM)  and Policy Control Function (PCF) during the registration procedure
  • AMF is responsible for selecting an appropriate Session Management Function (SMF) during PDU Session establishment
  • AMF is responsible for XnAP and NGAP Handover during UE Connected mode Mobility
  • AMF is responsible for Voice Fallback when 5GC is not supporting the Voice Service
  • AMF is responsible for IRAT (4G) handovers when UE moves to an area when no 5G Coverage only 4G Coverage


  • 3GPP TS 23.501 System architecture for the 5G System (5GS)

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