code: def requestPdpContextActivation(AccessPointName_presence=0):
      
      a = TpPd(pd=0x8)
      b = MessageType(mesType=0x44)  # 01000100
      c = PacketDataProtocolAddress()
      packet = a / b / c
      if AccessPointName_presence is 1:
          d = AccessPointName(ieiAPN=0x28)
          packet = packet / d
      return packet
docs: REQUEST PDP CONTEXT ACTIVATION Section 9.5.4