Ghost signals are referred to as alarm signals that come in on an unknown or different account within signal automation software. Incorrect programming or central station receiver line card errors usually are to blame. With some understanding of how they come in and how they can be dealt with, one can reduce the frequency of these signals.

How do ghost signals occur? When a central station has more than one receiver – as most do – each receiver must be given a separate identity, called a line identifier. When a technician programs the correct account number with an incorrect phone number in a panel, disastrous results may occur.

For example, a technician programming a panel with the central station identification (CSID) of 450-1234 could accidentally send signals to account number A1-1234. Instead of sending signals into the account for “Jimmy’s Burger Joint,” the burglary signals go to the account for the Johnson residence across town.

A receiver that has physical deficiencies also might be the cause. If it sends false data to automation software, this could cause the central station operator to take action on the wrong customer’s account.

Make sure your central station receivers are all in proper working order. Like a car, these receivers must be tuned up every once in a while; check the manual for details. A low battery, a short on the phone line, or dust on the line card terminals might be the cause of line card errors.

Ghost signals also may have a financial impact. Consider the consequences on a customer of dispatching due to an erroneous signal caused by equipment or personnel. This could lead to a loss of recurring revenue and time wasted investigating what happened. At the very least, the task of dealing with that customer – who may not understand the situation – could be unpleasant.


Tracking down and isolating the source of these signals is easy. Technology to assist in identifying ghost signals exists, but it is limited. The following devices can help locate ghost signals.

CALLER ID – This simple feature on all receiver lines can be helpful in many situations including trying to isolate ghost signals. Caller ID can help identify which panels are dialing in and when. A time index of signals being sent makes tracking down ghost signals an easy task.

UPDATE THE RECEIVER – A new central station receiver can make a difference. Almost all new receivers use Caller ID, have event filters and many other smart features specifically to reduce this problem. Most small- to mid-sized companies can accommodate their accounts with just one receiver.

SOME RECEIVERS CAN HANDLE UP TO 12 INCOMING PHONE CALLS AT ONE TIME – 24 with a redundant receiver. The benefits of having one receiver also eliminate the possibility of duplicating an account number across two or more receivers. Even one receiver capable of a four-digit alphanumeric account number can handle up to 43,680 accounts.

CHECK AUTOMATION SOFTWARE – Software currently in need of an upgrade or in the middle of an upgrade might have problems. When the central station receiver sends its information to the automation software, a transmission error may occur if the software “slips its mask.” That means that the data is coming in on the wrong line identifier. If masked wrong, this would have the same effect as ghost signals. This is an uncommon occurrence – I have seen this happen only once during my seven years in the alarm industry.


Along with technology, consider the human factor. You may use these tactics to acquire a lock on these problems:

CHECK SIGNALS – Receiving fire signals on an account that only has burglary zones listed is a clear indicator. Also, if you have two- or even three-digit zone numbers coming in on your account and you only have zone listings 1-8, pay attention – you might be getting signals on the wrong account.

CHECK YOUR FORMAT – Older alarm panels may be using 3+1 or 4+2 formats. This can be a dead giveaway in certain cases.

LOOK FOR SIMILAR ACCOUNT NUMBERS – A technician may transpose two or more digits in an account number. When trying to put account A1-1234 online, for example, he or she might send signals to account A1-1324.

PAY ATTENTION TO CUSTOMERS – If a customer was dispatched on and they claim that they did not even arm the system, they may be right. Ghost signals can come in even one at a time and then disappear forever.

LOOK FOR A LACK OF SIGNALS FROM OTHER ACCOUNTS – If a receiver is receiving data from a panel that is using the wrong format, it might cause the receiver to hang onto the line. In this same example, the panel might dial many times to send the same data because it did not get an acknowledgement tone from the receiver. This effectively can flood a receiver with false data and not allow other accounts to get through on the phone lines.

GUARD YOUR RECEIVER LINE NUMBERS – Regrettably, unscrupulous people who have receiver line phone numbers could do serious damage.

Ghost signals are a quiet problem that can affect more people than might be imagined. They can increase overhead costs in many ways, from false alarm fines to increased monitoring costs. They have the capacity to beleaguer central station operators and flood receivers.

Newer technology can be purchased to assist in dealing with these problems, but the most versatile instrument that every company has is the human brain. One alert individual can save a company thousands of dollars each year. One must remain vigilant – who knows what ghost lurks in the machine?