Leave me a voicemail and follow up an hour later with an e-mail saying, "I haven't heard from you yet."
There is a time-sensitive issue (i.e., you are on the way to an interview and need to speak with me urgently) or I have actually indicated to you personally that I would be getting back to you within this abbreviated timeframe.
But, if I just called you about a job and you are just returning my call...my outgoing message says I will return your call in "one business day." The business world moves fast, but an hour is NOT "one business day". Four hours is not "one business day." "One business day" means if you leave a message at 12:00 PM on Friday, I will return your call by 12:00 PM on Monday. Unless Monday is a holiday, in which case, "one business day" is by12:00 PM Tuesday.
I will certainly try to call you back sooner than one business day if I can, but being vaguely petulant about not being called back immediately doesn't endear you to any recruiter.
That said, it is absolutely fine to follow-up a voicemail with an e-mail. Just read and re-read your message to make sure it comes off as eager and not entitled.
Do: "Hi! I left you a message this morning about the position you contacted me for, and wanted to follow-up with an e-mail to provide a clean copy of my resume [Note: Great excuse for multiple contact, you're actually sending the e-mail to be helpful!] and just express again how excited I was to hear from you! This opportunity sounds perfect..." blah blah blah. (I know, it's a little hokey, but I'd rather someone attributes their behavior to over-enthusiasm than to some short-coming on the part of the recruiter.)
Don't: "I left a message for you this morning [Note: at 6:00 AM my time - my location is in my signature, do the math] but I haven't heard from you yet [it's now 9:45 AM my time, I've been at my desk for less than an hour and guess what: you are not the only candidate who exists]."