Welcome and thanks for posting. Since you don't have the HughesNet Voice service, it sounds like you're asking about the WiFi calling on your mobile service? You may want to check with your cellular provider whether they support WiFi calling.
If you have a tech or billing question and need help, please start a new thread in the appropriate board. Unsolicited Private Messages may not get replies.
Nothing can be done to make the latency below about 650 ms on the newest satellite and even higher on the older one. Cell phone WiFi calling will not work well at all, if it even works marginally it won't be of much use. Voice dropouts and lost connections being the norm.
VOIP or wifi calling just doesn't work over Hughes Net. It takes too long for the signal to go from your phone to the satellite and back. You could try "Over" to let those who you're calling know that you've finished your response. Might work with family and close friends but won't work for anyone else.
I have a Nexuxs 6p and use it with Project Fi and wifi calling is absolutely useless on Hughes. If the phone rings, I don't answer the phone but wait for the voicemail. If it's important, I walk out to the corner of my property where I get enough bars to make a call.
No one who has options like DSL, cable, or Fiber optic should consider Hughes