[Galaxy S 5 Android Development (Snapdragon)] Z00nkor:
I digged a little bit further about my voLTE problem and also found some info about LineageOS and IMS: https://github.com/LineageOS/android_frameworks_opt_net_ims

o2 IMS config (extracted from S5 VIA stock ROM):

<Settings>
<Connections>
<NbProfileHandle>1</NbProfileHandle>
<ProfileHandle>
<NbNetProfile>3</NbNetProfile>
<NetworkName>o2-de</NetworkName>
<ProfBrowser>o2 Internet</ProfBrowser>
<ProfMMS>o2 MMS</ProfMMS>
<ProfIMS>o2 IMS</ProfIMS>
<ProfXCAP>o2 Internet</ProfXCAP>
</ProfileHandle>
<NbProfile>3</NbProfile>
<Profile>
<NetworkName>o2-de</NetworkName>
<Editable>yes</Editable>
<ProfileName>o2 MMS</ProfileName>
<URL>http://10.81.0.7:8002</URL>
<Auth>normal</Auth>
<Protocol>http</Protocol>
<MTUSize>1500</MTUSize>
<Proxy>
<EnableFlag>on</EnableFlag>
<ServAddr>82.113.100.5</ServAddr>
<Port>8080</Port>
</Proxy>
<PSparam>
<APN>internet</APN>
</PSparam>
</Profile>
<Profile>
<NetworkName>o2-de</NetworkName>
<Editable>yes</Editable>
<ProfileName>o2 Internet</ProfileName>
<URL>http://m.o2online.de</URL>
<Auth>normal</Auth>
<Protocol>http</Protocol>
<MTUSize>1500</MTUSize>
<Proxy>
<EnableFlag>off</EnableFlag>
</Proxy>
<PSparam>
<APN>internet</APN>
</PSparam>
</Profile>
<Profile>
<NetworkName>o2-de</NetworkName>
<ProfileName>o2 IMS</ProfileName>
<Auth>normal</Auth>
<Protocol>http</Protocol>
<MTUSize>1500</MTUSize>
<PSparam>
<APN>ims</APN>
</PSparam>
</Profile>
</Connections>
<IMSSetting>
<NbSetting>1</NbSetting>
<Setting>
<NetworkName>o2-de</NetworkName>
<Version>2.0</Version>
<EnableIMS>true</EnableIMS>
<VoLTE>
<SMSoIP_Domain>cs</SMSoIP_Domain>
<EnableVoLTE>true</EnableVoLTE>
<EnableVoiceoverWIFI>false</EnableVoiceoverWIFI>
<EnableVideocall>true</EnableVideocall>
<EnableVoLTEindicator>false</EnableVoLTEindicator>
<Voice_Domain_Preference_EUTRAN>imspsvoicepreferred</Voice_Domain_Preference_EUTRAN>
<Emregencycall_Domain>cs</Emregencycall_Domain>
<SS_Domain_Preference>ps_only_psregied</SS_Domain_Preference>
<SS_PS_Control_Preference>xcap</SS_PS_Control_Preference>
<SS_CSFBwithIMSerror>true</SS_CSFBwithIMSerror>
<USSD_Domain_Preference>cs</USSD_Domain_Preference>
</VoLTE>
</Setting>
<Setting>
<NetworkName>TestBed</NetworkName>
<Version>2.0</Version>
<EnableIMS>TRUE</EnableIMS>
<VoLTE>
<EnableVoLTE>TRUE</EnableVoLTE>
<EnableVideocall>TRUE</EnableVideocall>
<EnableVoiceoverWIFI>false</EnableVoiceoverWIFI>
<EnableVoLTEindicator>FALSE</EnableVoLTEindicator>
<Voice_Domain_Preference_EUTRAN>IMSPSVoicePreferred</Voice_Domain_Preference_EUTRAN>
<Emregencycall_Domain>CS</Emregencycall_Domain>
<SS_Domain_Preference>PS_ONLY_PSREGIED</SS_Domain_Preference>
<SS_PS_Control_Preference>XCAP</SS_PS_Control_Preference>
<SS_CSFBwithIMSerror>false</SS_CSFBwithIMSerror>
<USSD_Domain_Preference>CS</USSD_Domain_Preference>
<SMSoIP_Domain>CS</SMSoIP_Domain>
</VoLTE>
<RCS>
<EnableRCS>FALSE</EnableRCS>
</RCS>
</Setting>
</IMSSetting>
</Settings>

[MENTION=3419717]cvxda[/MENTION]

Is there any way to make this work with LineageOS? I'm willing to test and help but I have no idea where to start... Please tell me if it's possible or not. If not I can stop searching for information about it and live without voLTE but imho that would be kinda lame for a voLTE cabeable device like the S5-Plus.