PFI
Packet Flow Identity
The Packet Flow Identifier is used to indicate a PFC (Packet Flow Context) associated with an LLC (Logical Link Control) – PDU (Protocol Data Unit). If the mobile does not support PFC or if the PFI is not known by the SGSN (Serving GPRS Support Node), then it will use the pre-defined PFI indicating best effort QoS (Quality of Service).