Help with setting up Tannoy speaker

[SimonL2020]

Hi

We have just migrated from a Mitel PBX system to a BT Voice SIP system.

The old Mitel PBX was connected to a Inter-M PA 4000 PA system via what looks like a standard analogue phone cable.

On the old system, you selected the extension for the PA system and made your announcement.

BT have provided us with a Cisco SPA112 and configured it for our network.

When we dial the PA system, we can see the level meter on the amplifier moving with the ringing sound, but it never picks up.

I've no experience of setting one of these up so I'm wondering if this is even compatible or we need to buy a new PA system.

Any help appreciated.

[Dan Lukes · Accepted solution]

OK. It seems no one is going to respond you, so I will try it despite i know nothing about Inter-M PA 4000 PA. According operating manual it can't work this way.

According picture on page 12 of operating manual, PA expects phone to be connected to TEL-IN. It mean PA is like PBX - phone can be connected to it. Such kind of phone port is known as FXS.

Even SPA112 is PBX like device. It's not phone - phone can be connected to it. It provide FXS port as well.

You connected two FXS (PBX-like ports) together. It just can't work. See What’s the difference between FXS and FXO? for more detailed explanation.

You need to have SIP device providing FXO port.

[SimonL2020]

After looking at the back of the PA system, I can see it will never work.

The 'phone' wire that connects the Mitel PBX to the PA goes directly into one of the audio inputs.  

So I can only assume that the Mitel outputs an audio signal to go directly into an amplifier.

[Dan Lukes]

As I mentioned already, a SIP<->FXO adapter connected to TEL_IN of PA may work. No warranty, of course.