Respectfully @Abhishek_TV Sir,
@sudher256 Forget Dual VoLTE,
Airtel & Idea VoLTE service both are still not supported in SRT.
FYI I have tried both but it doesn't work
Vodafone VoLTE is also not supported in SRT as per below link
This is your post back in July'18
Till date no such effort has been made from @smartron to add this basic feature which is now a days very common.