The site I use most generally turns out to be voip-info.org .
But! When you say VoIP, though, that's a pretty wide net. Not quite as wide as asking the same question about TCP/IP - but if you could be a bit more specific, you might get more helpful information.
Assuming your interest is in the open-source world, there are several projects that underly most of the applications out there. Asterisk is the best known. In the Asterisk world, there are, again, numerous projects and products based on Asterisk. Asterisk is a bit like Linux - the kernel might be the same, but the distros package functionality, and in different ways. You can implement an Asterisk PBX, for example, from "scratch" or use, say, Trixbox, which packages asterisk along with basic functionality "in the box".
Asterisk.org is the project home. The wikis are a good source of the current documentation on Asterisk functionality; also there are books on it, such the Definitive Guide from O'Reilly.
I've offered to give a BBLISA talk on Asterisk at some point in the future.
> Hi All. I've been doing some voip research at work, and wanted to see if any bblisaers have
> any recommendations on good web sites, forums, or mailing lists that are a good resource for voip.
> Also, any experiences that any of you would care to share with any voip system would be welcome.
> bblisa mailing list
> bblisa@bbli... > http://www.bblisa.org/mailman/listinfo/bblisa