Yes these are based on dated technology but these units (I have multiple TESTED units) are fantastic for professional radio to landline automatic interfacing.
Tara Systems (Australian) were a major supplier of this equipment in the 80's & 90's and these units were in use by many State Emergency Organisations, including Police.
TARA Radio - PSTN/POTS Telephone interconnect (Public Switched Telephone Network or Plain Old Telephone system = 2 wire)
Main system unit
System cable - 1
I only have a limited number of these manuals - first in will get the manuals until they have run out
Operator Handbook (original)
Installation and Programming manual (original)
Programming of system parameters is from the front panel - no special programmer is needed
I have multiple units, all have had limited testing (not going to air) as outlined below.
No other equipment is needed to get going with these - connect your landline, connect to your transceiver RX/TX audio lines and RX/TX control and away you go.
Proper telephone/equipment isolation with Austel approval
Briefly, you can take a landline call, isolate the conversation from the radio communications or patch to the radio for landline to radio communications.
Authorised radio mobiles can also access the system (using a 2 digit DTMF code) and make their own unassisted calls direct to the landline from their mobile location.
Incoming landline calls can also be automatically patched to the radio system without any operator assistance.
Built in multi-level access security and in the event of unauthorised codes being used, the unit can be programmed to "lock out" the user.
The LCD display shows current mode (TX-RX-Idle) user code, telephone numbers etc so you know exactly what is happening with the system.
Very flexible, many parameters are possible via the programming and yet it is relatively easy to understand and use.
All tests made on the landline side of operations ONLY - I did not readily have a transceiver available for the radio patching but I did look at the audio out and sent test tones into the audio input to simulate a transceiver being connected.
You need to supply 8-16V DC @ around 500mA (normal operating current is around 150mA)
Checked landline outcalling, monitoring via the handset, DTMF signalling - all functioning correctly.
Analog audio signalling to the transceiver and from the transceiver also checked fine.
These units are tough - that's a solid steel case and the handset is actually from Tytel, and lightweight. These were built for heavy - reliable use every single day.
It uses a magnetic microswitch for off-hook signalling, NO mechanical switch.
The handset also has a low power audio amplifier built in (instructions on how to enable this are in the manual) for loudspeaker operation.
The main control unit also has a monitor speaker.
These systems can be used standalone or because they use a buss system on the outputs, multiple unit configuration is possible across a common communications buss.
I have stripped back the supply lines on the cable (for easy identification) and the manual outlines the signals available on the D25 connector.
You will not get caught out if something goes wrong (lightning strikes are a common issue) as I also have a range of spare parts for these units.
If interested in getting more details about these, I am making available the installation and programming manual in pdf electronic format to ANYONE who asks for it.
These manual's detail the extensive facilities available.
The pdf is in secure/locked mode - you can ONLY view it, you cannot print it or alter it.
Just email your request for the document and I will send it to you, along with the password to open it.