well, i was thinking along the lines of this:
in sip.conf, we’ll have the following device:
[acme-2001]
let’s say this person acts as an operator…
in extensions.conf, we can have the following extensions point to this device:
exten=>2001,1,Dial(SIP/acme-2001) ; direct extension
exten => 0,1,Dial(SIP/acme-2001) ; operator extension, put in your incoming calls context
this way, internal users can dial extension 2001 to reach this person, but external callers will be able to dial 0 - it allows you fine grained control over who can call who, basically.
this is an extremely crude example, but it’s also fairly common. this may not be what you were thinking, but when i said mesh, i meant a matrix, where devices can have multiple extensions tied to them, and vice-versa - you have total separation of the ROUTING of calls and the DEVICES that are being routed to (that is a bad sentence, but you get my drift, hopefully)…