Concept, check an Microsoft Exchange server for freebusy information against a calendar. This could be used for both user calendars - to send straight to voicemail (auto do-not-disturb) or for resource scheduling - such as maintaining a calendar for the offices opening and closing times - which can then be set from an Outlook client.

The file is opensource - and developed by Nick Knight from Omniis (www.omniis.com).

The dial-plan

Example dial plan.

exten => 151,1,AGI(freebusy.php|myexchangeserver|bob|bobspassword|nick@omniis.com)
exten => 151,2,GotoIf($[${FREEBUSY} = 0]?3:4)
exten => 151,3,Dial(Sip/nick)
exten => 151,4,Hangup()

the freebusy.php script needs installing into the agi-bin and you are away.

freebusy.php

The file can be found at freebusy.tgz