Download IH320 Wiring Diagram 1 

Download IH320 Wiring Diagram 2

How can I get another set of installation instructions for my hands-free phone?

Here are the links to various suppliers:
Wurtec Helper Phones
Go to their Quick Links for programming help, or their Technical Page for the installation

K-Tech Phones
Go to their Tips & Techniques, then Emergency Communications (Telephones), and select the information on the model in question.

For Vandal Proof Products or EMS phones, contact one of Innovation’s Parts Sales/Customer Service representatives.