Depending on which ESI phone you have, use the appr opriate diagram (below) to connect it. Each diagram represents the panel on the phone’s underside. Note: The “Top of phone” and “Bottom of phone” references in these diagrams show the correct vertical orientation of the phone — i.e., the part with the display is the top.
I haven't used this device for an extended period, but since there are no mechanical parts, I expect that it will last. We have been using a professional on hold service for many years at about $60/month. The box that the professional company gave us sounded great when customers would call from a Lan Line. But, when calling from cell phone the voice messages were lower volume and the music would sound horrible. Music keeps cutting in and out and sounds very staticky. So we decided to save some $ and cancel our subscription and buy this unit. We are using the default music and voice messages that came preloaded instead of doing our own music and messages.

User’s Guide will introduce you to the wide variety of fe atures offered by your ESI phone system and how to use your phone effectively to achieve maximum benefits. What it covers • 48-Key Feature Phone (Digital, TAPI, IP and Remote IP) • 24-Key Digital Feature Phone • 12-Key Feature Phone • 60-Key Expansion Console These are used
“Superbly written copy and extremely dry humor that was a perfect match for what could've been a dull subject. I laughed out loud at points, and when a caller starts with that reaction, it's a great way to start a conversation.” - Jim Hausfeld / On Hold Messaging Association's MARCE Awards Judge