The joy of OHIS – Open Headset Interconnect Standard

The Open Headset Interconnect Standard (OHIS) is actively being developed by Mark N6MTS. Information is available at

There are so many different standards for microphone, headphone, and PTT that it is improbable that one could take their preferred headset and connect it to any radio without an adapter. In a multi-user environment, such as a club shack, Field Day type event, or an EOC, they would need a full-mesh of adapters to ensure any
user can connect their own headset to any radio: O(N^2) adapters.

With the Open Headset Interconnect Standard, or OHIS, the club/EOC can build/buy one adapter for every radio which stays with that radio, and the user only needs to build/buy one adapter for their specific headset which stays with their headset, and now they can achieve full interoperability with only O(N) adapters.

The connector standard for OHIS is the familiar RJ45 (aka 8P8C Modular) plug. The selection of this standard is great for low-cost and availability of cable, plugs and general mounting hardware.

The pinout of OHIS is carefully chosen to have a signal/gound on each twisted pair of a standard Ethernet wired cable. This means you can get a patch lead out of your junk box, it in half and you have two half-wired cables ready to go, just attach transceiver plugs are it’s ready.

For making cables to connect radios to the URC, the OHIS RJ45 jacks are a simpler and easier option that trying to wire a 3.5mm TRRS jack plug, and the connector is much easier to handle.

The OHIS connectors on the Universal Radio Controller are wired as a pass-through, so can sit on the line between the Radio and the User of an OHIS connection. The URC is a ‘User’ device so is able to transmit and receive using the internal sound card and PTT control, whilst at the same time allowing the human user to use the radio when the URC is idle.

Of course you can just use one of the connectors on the URC and connect it to your radio with a simple single lead.