two weeks seems reasonable, esp. if the committee has to split meetings to conduct the phone interviews… and then have a final meeting to deliberate which to invite out.
three weeks seems like you're probably not a top candidate. typically, there are candidates that are "in limbo" b/c the committee hasn't selected them as top candidates to bring out for initial interviews but they keep waiting in the wings in the off chance that none of the top candidates work out.
we actually are dealing with this situation in our current search and HR explicitly asked us not to contact candidates who might be second-tier as to "not make them feel bad" because they're not top choice. i don't love this process b/c i'm sure candidates rather know that while they're not completely out of the running, they shouldn't keep waiting and should pursue other jobs.