Hi Mike,
No experience with Vopium myself, but the address they gave you sounds like it is their proxy server information. Again, I have no personal experience with them, but I would guess that the
rtsip.vopium.com is their proxy server. For username and password, you would need an account with them. So you are best off contacting them directly for this information, after you have signed up for an account.
I looked at their website, and it seems they have a Support option right there. So, perhaps you can give that a shot and see what they recommend!
pc44