There is certainly a chance they won't let you know if they were vague in the phone interview. Thus far, my phone interviewers have all mentioned a time line at the end of the call (e.g., we'll be making on-campus visit decisions by next week, etc.) and stuck to it. For example, I've received a "you are not in the top 3 but we still like you and may ask you to visit in the future' email during the promised time period and calls for on-campus invites. During one phone interview they explicitly told me they would let everyone know either way.
It will be tough if you are left in limbo, but don't assume rejection if all is quiet. You might be down on the list (if things don't work out with the top picks), but that's ok. The way I see it, if I get a job offer, I don't really care if I'm #1 or #10! At this stage it is important to remember that you've already been deemed a desirable candidate, and often they are just going with their perceptions of the best fit out of a number of good options. That is, they are not necessarily 'rejecting' you, they are 'choosing' someone else.