What is the difference between a Partylines (PL) and a Fixed Groups (FG)? And what is a Sort Group?

See attached file


What is the difference between a Partylines (PL) and a Fixed Groups (FG)?

And what is a Sort Group?



There are several types of ways we communicate in the intercom world. It used to be we all used Partylines to communicate. We’d all talk on one big conference and choose when to be heard by engaging our talk button and when to listen by turning our volume knob up or down… or by simply taking off our headset!

Now that we use more sophisticated matrix-based systems, we can enhance the ways we communicate with several other ways to interact.

So, let’s look at the three basic forms of communications:



Point to point.   This is when we talk privately from one device to another.  Think of it as you would when talking to a friend on your telephone.  I push a button with your name on it and, as long as I hold it, you hear me. When I program these labels on a panel or belt pack, I only need to program the TALK Label, as the matrix or base station will automatically open your listen path from me to you for the duration of my holding down the TALK button.


Partyline.   A PL is a conference where more than one user can communicate (in a full-duplex fashion) with other users.  The partyline allows a user to choose when they talk to the PL and when they listen.  One engages the TALK circuit to the PL and all listening will hear that. One can un-engage the listen to the PL or at least turn down the volume, to not hear the PL when they choose. Party lines are the most common form of intercom and have been around since the beginning of these production intercoms since the 1960’s. Everyone talks when they choose (by pushing the TALK button) and listens when they choose (either by engaging the LISTEN lever or button, in the case of the panel or by turning up or down on the volume know in the case of the BP).  The PLs are broken down into channels, or separate paths, as needed for separation of conversations according to the required workflow in the system.


Fixed Groups, or Groups. A GROUP is also a conference where more than one user can communicate. However, the structure is a bit different from the PL. We put devices (panels or belt packs) into groups as “members”.  When one pushes the “audio group” (for example) button, every “member” device will automatically hear the talker for the duration of the time that caller keeps the group button engaged. The panels/BPs do not need a listen from that group, as the matrix or base will automatically open a listen pathway to all members of that group from the caller.  Think of it like a point to point, but this is a “point to many”. Even though the other devices might not have that group programmed onto their panel/BP, the hear the caller since their device is a member of that group. If you hold up your hand with your thumb (caller) and your pinky (member) sticking out, that would be a POINT TO POINT. Now point all your fingers up.  Your thumb is calling all the fingers.  That’s a GROUP.

Sort Groups are groups of items such as controls, fixed groups, IFBs, interfaces, panels and Partylines that can be treated as a single item programmed to a panel or FSII BP button (or label). A feature of newer versions of the EHX software and firmware allows for a panel or FSII belt pack label to act as a selectable list of ports or conferences that may be chosen by the user.  We make the SG with just the choices needed by that operator, so as not to make the list too long and keep it manageable. Once the operator chooses that item for the button, it remains there until the next time the operator wants to change it.