There are 5 Video Relay Service Providers, all for profit, nationwide. The VRS process has a sign language interpreter, based anywhere in the US, to answer calls via video from a deaf caller, anywhere in the U.S. The deaf caller, once connected to an interpreter, provides the interpreter with the phone number they want to call, and the interpreter (unfamiliar with the person, organization, or company they are calling), calls the number through a telephone call on behalf of the deaf caller and talks to the recipient, interpreting the menu tree, conversation, etc. The deaf caller and hearing recipient are entirely dependent on the third party interpreter, their skill level, their knowledge (or lack thereof) of the specific organization or industry, regional signs, etc.
https://www.youtube.com/watch?v=eb7eU-hl6QQ&t=10s