Am I correct in assuming this is possible?
How about this?
voicemailserver is another asterisk box with the user provisioned in sip.conf, and relevant entries to route to voice mail on that box with extensions.conf and voicemail.conf. For the second example, I assume Asterisk can do SRV/NAPTR to look up the relevant host to use?
Is this routinely done? Is this the best way to separate out the voicemail from one asterisk system to another? Is SIP the best protocol for this, or would IAX be better? For SIP, how is the authentication done? Does the desatination server just ask for credentials and compare it against what it has in sip.conf (as if the first asterisk server was a client) ?
Oh, and this is important. When the Dial command is executed, does the first asterisk host stay involved in the RTP stream, or only the second?