I’m not an expert in this myself yet, but here is what I think:
Traditional switches can still be used in VoIP. VoIP could be thought of as a transport medium, with the switching elements remaining unchanged.
But, with IP phones, within a LAN, calls can be switched using Ethernet switches or concentrators in wiring closets (each IP phone having a unique IP address).
The Gatekeeper doesn’t really switch, although it does have a control function, provides access control and address translation (where necessary).
I don’t know how carriers are switching (but I suspect that not many are!).
As for standards: there are many relating to VoIP. H.323 (with Q.931) and SIP provide the signalling and control. I think these two standards are tending to converge, but H.323 is more popular with carriers, and SIP is more common on the enterprise. There are many other protocols involved in control and transmission.
We will be adding links to such documents in our new searchable VoIP Directory (more on that in a week or two). We will also present some technical papers on the protocols, although initially, these will concentrate on transission.
If you have signed up for our newsletter (see form on home page), then we’ll email you with progress reports.
VoIP Calculator Webmaster (TOM).