if i remember correctly - you ring an ACD group and agent does not answer, they are logged out of the group, so eventually all calls will follow the divert on no available members (set as CDINI) anyway. The call will be placed back in the que each time so each agent will get made unavailable as the call routes round the group. So if you leave the building, the first maybe one or two calls could be lost if many members, but very shortly it will follow the divert. If this is voicemail, dial into your voicemail from a mobile outside and change the greeting for the mailbox to state the emergency.
You are on ACD/CCM not Solidus i think from your questions? If you are on Solidus this can all be done much better.
best parnum