This product IS NO LONGER AVAILABLE. If you have an IP7-SE8 and require support for half duplex audio using the speaker as both a speaker and microphone (talkback or single transducer mode), you should look at the IP7-FX – IP Intercom and Paging Amplifier.
The IP7-MSR-BRD – Mic/Speaker Relay Board on an IP7-SE8 allows an 8-Ohm speaker to be used as both a Microphone and Speaker. The board incorporates a relay to automatically switch the speaker between the IP7-SE8’s Microphone and Speaker inputs. A suitable 8-Ohm re-entrant capable speaker or horn is required to ensure proper gain.