Never leave your number. Do not let them put you through to voice mail. Important people, even vaguely important people, will not call you back ever unless you yourself are important. Even then you're taking a chance. (but i'm sure you've figured this out by now)
What I do is ask when exactly they will be back and how exactly I can reach them at that time. Then call back, repeatedly if needed. (often is) The only way to get results is to be as rude as you can be without offending anyone. One guy I really couldn't get through to during the week so I ended up leaving my home phone number on his voice mail and asking him to call me over the weekend. (He actually did, too!) You could also try asking for an email address, though this is iffy because project managers tend to get 200+ emails a day.
A+ Entry
What I do is ask when exactly they will be back and how exactly I can reach them at that time. Then call back, repeatedly if needed. (often is) The only way to get results is to be as rude as you can be without offending anyone. One guy I really couldn't get through to during the week so I ended up leaving my home phone number on his voice mail and asking him to call me over the weekend. (He actually did, too!) You could also try asking for an email address, though this is iffy because project managers tend to get 200+ emails a day.
~feelin ur pain~