VoWiFi & ViLTE Codec Issues: Failures, QXDM Keys, Response Codes & Troubleshooting?

 Voice over WiFi (VoWiFi) and Video over LTE (ViLTE) rely on IMS (IP Multimedia Subsystem) for voice and video calls.

• VoWiFi uses Wi-Fi instead of LTE for call transport.
• ViLTE enables video calls over LTE without third-party apps.

    

Layer-Wise Troubleshooting Approach for VoWiFi & ViLTE Codec Issues:-

Step 1: IMS Registration Check

• Use: IMS_Registration_Status

Ensure IMS registration is successful before making VoWiFi/ViLTE calls.

✅ Fix: If IMS is not registered, reset IMS settings and verify VoWiFi/ViLTE provisioning.

 Step 2: SIP Signaling & Codec Negotiation

• Use: IMS_SIP_INVITE, IMS_SIP_183_SDP

Check codec list in SDP message (AMR-WB, EVS for VoWiFi & H.264 for ViLTE).

✅ Fix: If codec mismatch, ensure UE and IMS core support the same codec.

Step 3: RTP Packet Flow Analysis

• Use: IMS_RTP_Stats, IMS_Media_Statistics

Check for packet loss, jitter, and latency in RTP flow.

Fix: If high packet loss, optimize QoS, increase jitter buffer.

Step 4: WiFi Network Analysis for VoWiFi

• Use: WiFi_Stats, WiFi_SNR, WiFi_Channel_Interference

Check WiFi signal strength, interference, and bandwidth.

Fix: If weak WiFi, switch to 5GHz, avoid crowded channels.

 Step 5: QoS & Bearer Prioritization

• Use: LTE_EPS_Bearer_Context_State

Ensure VoWiFi (QCI=5) and ViLTE (QCI=2) bearers have high priority.

Fix: If incorrect QCI, force correct bearer configuration.