I want to connect 2 SPA2100 directly to each other thru an IP network in order to enable a voice communication between the phones behind them, Can I do that?
I know I can do that with 2 H323 ATAs but I think these adapters support SIP only.
Yes, it can be done. The SPAs usually are
registered to SIP proxies/registrars, but
they can be configured for a direct peer-to-peer connection. Just configure the dialing-plan.
Or if you want the quick dirty way - right below the dial-plan there is a menu option "Enable IP dialing" (or something like this). You can dial between the SPAs via their IPs, but I doubt you will like to use it.