Unfortunately, it is often hard to get through to a busy fax line at at large company.
The Dreamhost “Contact Us” page lists a different Fax number, but I assume they may have sent you a different one for your purpose (and now that you have published it here, it might be even harder to connect to!) Even though the Contact Us page makes it very clear that “Technical & Billing support is not available via FAX”, I suspect that many still send their, “OMG! My Server is Down!” stuff to it, which only serves to make it very hard to connect to.
I suggest you keep trying, and don’t hesitate to generate a Support Request from the Control Panel if you just can’t manage to get through. As a last resort, you could also contact them via the “sales” contact form Good Luck!