I have a client who wants us to remotely load customized voice prompts into his auto attendant. He knows how to do it on premise, but we need to remotely access the system to get our professional prompts entered. Locally, he enters Intercom to do it. Can anyone help us figure out how to remotely do the same thing? Thanks in advance.

You will have to do it the same way he does only you call in then go to the Admin. It will have to be done over the phone.
I know of no other way on the VS mails