Custom multiple welcome messages

[ASTK]

Hello,
I’m working in ISP company. Sometimes we have planned maintenance in network so we need to turn off some city.

Currently we have welcome message. Customer can choose number (1 for technician help, 2 for invoices etc).

Is possible to make custom welcome messages?
We have recorded names of cities, i.e.:

city_a.wav
city_b.wav
city_c.wav
maintenance.wav

If there is maintenance, I want to turn off standard welcome message and want to turn on ie:
maintenance.wav - city_a.wav - city_c.wav

Is possible to do that? How?
Thank you

Currently we have this only:
[IVR]
exten => _X.,1,Background(welcome/welcome_message)
same => n,WaitExten(5)

[johnkiniston]

Use the ASTDB to store a variable saying you are in maintenance mode.

Background(${IF($[${DB(family/key)} = VALUE]?maintenance&city_a:welcome/welcome_message)})