4G/LTE, VoLTE, VoWiFi, ViLTE

VoWiFi
https://www.gsma.com/futurenetworks/technology/vowifi/
https://www.metaswitch.com/knowledge-center/reference/what-is-vowifi-voice-over-wifi

Difference between VoLTE vs VoWiFI?
https://www.comparlo.com/question/what-is-the-difference-between-volte-and-vowifi/
https://ovoocado.com/5-things-about-volte-vowifi/

EPC
https://searchnetworking.techtarget.com/definition/Evolved-Packet-Core-EPC

Process for Lost & Found at Delhi Airport

ArticleId can be determined using the search by date page.
You have to visit the Lost & Found Counter at T3 or T2 and tell them the article id.

https://newdelhiairports.com/lost-and-found/
https://www.newdelhiairport.in/airport-guides/lost-and-found