Not All Telephone Systems Are Created Equal

In order to have music and messaging playing on one’s telephone system, the telephone system must have the parts and circuits to support message-on-hold.   The telephone industry refers to this feature as “MOH”.  Usually MOH support is found when the telephones are part of a “telephone system”…meaning that there is a central “brain” …or KSU (for Key Service Unit).

What is a KSU?

A KSU is a box about the size of a briefcase, usually hanging on the wall in a room with the routers, servers, telephone wires, water heater or even in a closet.  KSU stands for Key Service Unit.  It’ll say the name of the telephone system on the KSU. (e.g.: Avaya, Panasonic, etc)  The KSU is where all the telephone lines are connected.  The job of the KSU is to provide support for the many features we enjoy in today’s telephone system such as multi-line use, intercom, hold, paging, as well as input capabilities for background music and messages-on-hold.  The KSU is also the device that monitors which lines are on hold and makes sure the On Hold audio is only heard on those lines that are On Hold.

If you can locate the KSU, now it’s necessary to verify that it supports MOH.  This can be determined from the owner’s manual or by calling the local telephone dealer that services your KSU.  Some KSU’s have a music-ready jack on the outside, others have them hidden, and still others need to have the jack installed by a qualified telephone technician for a fee.

If there is no KSU to be found, the phones probably operate without a KSU.  This is known as a KSU-less phone system.  These systems have plenty of great features; however they do not support MOH.  (KSU-less phones are made by companies including AT&T, GE, Panasonic, RCA and others.)

Or, it is possible that you have subscribed to a “cloud based” or “hosted” service, whereby the operating software running your phones is off-site at a service provider or carrier site.   In this case, we would need to know the name of your provider and a contact phone number of your sales or technical rep.  

In any case, it’s always fine to call us with the make and model number of your telephone system and we’ll do the research for you.