VRS = video relay service
My primary communication is American Sign Language (ASL). When I make calls, I dial using the VRS app that opens a video chat window. I see the ASL interpreter sign and the interpreter speaks my signs. There is also an option of VCO (voice carryover) where if I want I can speak for myself yet, when the hearing person on the other end speaks, their words are signed to me. See sorenson.com for more info on how this works. Of course if you do not sign then that is not an options available.
I mostly just sign but I have used VCO during the interviews since everyone seems to want to start with a phone interview. I found I had been luck of getting to the next level when I used VCO than if I just signed and let the interpreter voice for me.