door units not ringing phones

[jonta]

On the control panel when a phone is connected to the (TEL-OUT) terminal and goes off hook it should be able to connect to the system when * code# is dialled
It does not do this
When the intercom is pressed at either door ringing current should be sent to any phone connected to the  (TEL-OUT) terminal
It does not do this
any ideas as to problem
this is a system installed by others some time ago and as far as i am aware the door intercom has never rung phones
the intruder alarm functions ok

[slychiu]

It appears that the offhook detector may not be working

Can you remove the telephone line from TEL IN and leave the TEL OUT connected. Wait for about 1 minute
The \"Phone Trouble\" warning should come on, ie the keypad should beep fast and the LCD should show \"Phone Trouble\"

This means the system has detected loss of voltage on the telephone line.

Now lift the handset. You should hear \"Phone Trouble\" on the phone. If the phone is dead, it means the offhook detection is not working. The CM9000 PCB should be repaired or replaced

What is the serial number on the PCB, you should see P or C followed by 6 numbers
ef P123456

[jonta]

thanks for your input
i will check these things when next onsite
and will get back to you