Voice communication demands consistent low latency and minimal jitter, which the default best-effort bearer cannot guarantee. When a VoLTE call is established, the PCRF instructs the PGW to create a dedicated bearer with QCI 1 parameters. QCI 1 specifies a guaranteed bit rate bearer with priority level 2 and a maximum packet delay budget of one hundred milliseconds. This ensures the LTE scheduler always reserves sufficient radio resources and prioritizes voice packets over background data traffic.