Phones powered down and won't come up

[ilubet]

No one was making any change on the system and randomly all the phones at the location powered off.

The IP office unit is still on and i can connect to it through IP Office R7 without any issues. When I call a phone number on the system is just goes straight to voicemail.

Any idea as to what caused this and how I can fix it?

[zakabog]

What type of IP Office is it? Are the phones all on an expansion module? When you open up System Status what do you see for the ports with the phones in them?