This information is provided without warranty – although I have been using this configuration successfully for over 12 months.
In FreePBX there is a module which has changed it’s name but remains an extremely useful one. Day/Night control, now called Call Flow Control, allows you to set a toggle-switch to change how a call is routed within the system. Typically this could be a Day or Night mode service, but you might also want a ‘We are closed for Christmas’ message for example. Using an announcement as the ‘night’ destination, using a recording linked to a feature code before going to a voicemail box, gives you a very quick way to temporarily close the office, with whatever message your users want to record themselves.
However, the module has a limitation; it only allows you to setup Callflows 0-9, for a total of 10 call-flow options. Should you need more than this, you would either need to program them manually, or else you can edit the module thus:
(This information was taken from here: http://www.freepbx.org/forum/freepbx/users/number-of-day-night-mode-controls-available-in-freepbx although this guide is a more basic version of the proposed patch)
(the folder is still named daynight even when the module in FreePBX is named CallFlow)
As noted on freepbx.org link, this doesn’t update any existing callflow controls, so if possible you’ll want to do this before you set any up. In theory there’s no reason that 1-9 shouldn’t still work alongside 01-09 and 10-99; you’d just potentially have *280 and *2800 as 2 separate callflow toggles.