QFI vs 5QI

QFI: Qos flow indicator

This indicates number of QOS flows in a single PDU session like for example in a IMS session there will be a signalling flow and one more IMS PDU for a voice call.

for each PDU session in IMS indicated with a number starting from QFI 1 and 2 or as per 3GPP spec 23.501 this QFI can also be equal to 5QI value.

5QI: 5G QoS Indicator

This is similar to QCI in 4g. These are standard values defined by 3gpp spec. To illustrate for ims signalling 5QI should be 5 and for voice call 5QI should be 1.

Snippets:

2025 Mar 17 18:12:15.971 [06] 0xB800 NR5G NAS SM5G Plain OTA Incoming Msg — PDU session establishment accept Subscription ID = 1     

qos_flow_desc

      num_qos_flow_desc = 1 (0x1)

      qos_flow_description[0]

        qfi = 7 (0x7)

        opcode = 1 (0x1) (Create new QoS flow description)

        e_bit = 1 (0x1)

        num_parameters = 2 (0x2)

        params[0]

          params_id = 1 (0x1)

          length = 1 (0x1)

          qos_flow_desc_params

            _5qi

              _5qi_value = 5 (0x5)

2025 Mar 17 18:12:37.814 [96] 0xB800 NR5G NAS SM5G Plain OTA Incoming Msg — PDU session modification command Subscription ID = 1 

      qos_flow_description[0]

        qfi = 1 (0x1)

        opcode = 1 (0x1) (Create new QoS flow description)

        e_bit = 1 (0x1)

        num_parameters = 6 (0x6)

        params[0]

          params_id = 1 (0x1)

          length = 1 (0x1)

          qos_flow_desc_params

            _5qi

              _5qi_value = 1 (0x1)