Set up google to send you all posts to the web that include keywords like - Voice talent wanted, voice talent needed - male voice over wanted - character voice needed... Enter as many keywords as you can think of & when someone makes a post anywhere on the net, google will email you a link to the post. Lots are Craig Lists postings & may not pay but if you field through them, some of them pay decently. Also freelance.com I believe it is - a good source for VO projects but it is a bidding site mind you... that can get yucky with talent trying to under bid each other. Many.com - starsearchcasting.com I believe it is. You have to dig through these sites but they are free...Nothing compared to a site like ours. I know - I am biased... But if you want cheap or free - these other sites can sometimes provide a decent lead... Hrmmm... Backstage I think it is called has casting calls as well.
I'm not sure what the best source is, but I think one option would be ask around in your home town and see who is hiring VO talent. Look-up other VO talent locally as well as anyone who might teach VO and are active in the VO community to see what they suggest. One of the places that is suggested where I live is to volunteer your time to read for the blind. They typically need people to read and record material but they don't have a budget to pay a pro. Also, non profit orgs may need someone to record their outgoing phone messages. You could offer your services to them and build creds along the way.
Voice123 is a minefield for newbies. Its selection system penalises you for auditioning too much - regardless of whether your voice is suitable or not, whether you have been invited to audition or not, and regardless of how many times they have reminded you to audition because the voice seeker has not had a good response. It needs work...
I have been on Voice123 for over a month and not got past the audition stage.
Very useful for examples of real voiceover requests to practice.