25. Digi ViLTE

Video over LTE (ViLTE)

"ViLTE uses the same control plane protocol as Voice over LTE (VoLTE), namely the Session Initiation Protocol (SIP). The IMS core network along with the applicable Application Server (AS) performs the call control. ViLTE uses the H.264 codec to encode and decode the video stream. The H.264 codec delivers superior quality as compared to the low bit rate 3G-324M codec that is used in 3G conversational video calls.

It is vital that ViLTE video calls are allocated appropriate quality of service (QoS) to differentiate and prioritize this delay and jitter sensitive conversational traffic from other streaming video traffic that is not as delay or jitter sensitive. The mechanism used is called QoS Class Identifier (QCI). The ViLTE bearer traffic is typically allocated QCI=2, and the SIP-based IMS signalling QCI=5" - Wikipedia


Specifications:
https://www.gsma.com/newsroom/wp-content/uploads//IR.94-v10.0.pdf

During a ViLTE call, the phone has 4 connections (bearers)

• Internet, here 200/50Mbps
• VoLTE/ViLTE - SIP signalisation, 512kbps,  not shown in the screenshot below
• Audio connection, here 44kbps
• Video connection, here 408kbps

Samsung S8 to Xiaomi Redmi Note Pro ViLTE Call

Digi VoLTE & ViLTE calls do not use preconditions . S8 to Xiaomi call:

Samsung proposed codecs in SIP Invite:

The codecs chosen by Xiaomi:

The phone asks for 700kbps (AS=700) +4.8.+14.4 =720kbps payload thoughput for video, maybe around 800 at the LTE level bearer, the network provides just 408kbps, probably what's statically configured in P-CSCF. The value is too low, thus the bad quality of the video call.


ViLTE activation in any rooted Samsung:

1. CSC : customer.xml:  change the Enable Videocall to: true

<IMSSetting>

      <NbSetting>2</NbSetting>
..............

 <Setting>
        <NetworkName>Digi.Mobil</NetworkName>
        <EnableIMS>true</EnableIMS>
        <VoLTE>
          <EnableVoLTE>true</EnableVoLTE>
          <EnableVoiceoverWIFI>true</EnableVoiceoverWIFI>
          <EnableVideocall>true</EnableVideocall>
          <EnableVoLTEindicator>true</EnableVoLTEindicator>
          <Voice_Domain_Preference_EUTRAN>imspsvoicepreferred</Voice_Domain_Preference_EUTRAN>
          <Emregencycall_Domain>cs</Emregencycall_Domain>
          <SRVCCversion>10</SRVCCversion>
          <SS_Domain_Preference>cs_always</SS_Domain_Preference>
          <SS_CSFBwithIMSerror>false</SS_CSFBwithIMSerror>
          <USSD_Domain_Preference>cs</USSD_Domain_Preference>
          <EnableSMSoverIP>false</EnableSMSoverIP>
        </VoLTE>
      </Setting>
    </IMSSetting>

2. Open IMSSettings : / IMS Profile / RDS Romania for IMS APN  / Service / LTE : check mmtel-video ; WiFi: check mmtel-video / Back / Save / Restart / Enjoy ViLTE if it's allowed by your operator!