Twenty Five Little Known
Telephone Tips for
Private Investigators

By Ralph Thomas


 Most people think that the standard weapon used by most private investigators is a gun. The fact is, the most powerful weapon a private investigator uses is the telephone. Knowing all you can about them when practicing your profession is important. It's the telephone, not a gun that is the most important piece of equipment a private investigator uses. The telephone brings you both business both new and old and is the one major communications medium you obtain information with. Product knowledge on it's use as it relates to your profession is of extreme importance. This article gives you some general but little known tips about private investigators use of their major weapon, the telephone. Some of them employ little techniques that are quite useful well others require special equipment. In the case of those that require special equipment, I'll lead you right to the web page for review.

Anonymous Calling: Outgoing And Incoming

The number one question these days about private investigators and telephones is how to make calls anonymously without revealing your caller ID stuff and how to answer calls coming in when you are undercover or under pretext. Here are some answers.

Tip One:
Call the operator and tell her that every time you dialed a certain number, you are getting an "all circuits are busy" message. She'll dial the number for you which then avoids caller ID. It's important to note that some telephone service areas offer caller ID blocking techniques you can employ any time on your phone. To find out, just call your telephone service.

Tip Two:
On most phone systems, you can hit *67 which blocks your caller ID information that goes tough.

Tip Three:
Set up a separate unlisted and unpublished line in your office for receiving calls and give this number out when you are under pretext or want to avoid mentioning who you actually are. Always answer the phone, "Business Office."

Cell Phone Tips

Tip Four:
To find out what carrier a person has for their cell phone, simply call the number when you know the phone number is not in use. The recorded message about the number not being in use at this time usually tells you what carrier the subject has.

Tip Five:
To trace an old cell phone number, go to the cell phone service and tell them you are interested in using the number but want to know who had the number before you. They will usually look it up and verbally tell you the information.

Tip Six:
Many investigators don't know it but there are several cell phone directories posted on the net. Here are the major ones:

Mobile Digits

Cell Phone Directory

Dialed Number Info From Recorded Calls

Tip Seven:
When a telephone call is recorded, there is a new self-contained long play tape recorder on the market that will log both incoming dialed numbers and outgoing dialed numbers. It's simply called the R2D2 Long Play Automatic Telephone Recorder. You will find information on it at:

R2D2 Telephone Recorder/Two Way Info Logger


Tip Eight:
If you already have purchased recording equipment and just want a decoder that will decode the dialed number for you, you can one that will decode it by playing the recorded tape back. You can review the Decoder at:

Dialed Number Decoder

Keeping Your Line Secure And Free Of Eavesdropping

Tip Nine:
There is a new generation telephone line monitor and analyzer on the market that keeps your telephone line free of bugs, wiretaps, hidden tape recorders and extension line pick-ups. This unit is unique in that it not only detects them, it also stops them! Simple to operate, you just hook it into your telephone in 30 seconds or less! It's called Safeline and it can be reviewed at:

Safeline 2001

For a completely self-contained secure phone that is inexpensive with countermeasures built right into the telephone see:

SecurePhone 2000

When Using Wireless Phones

Tip Ten:
The convenience of a wireless phone is nice but it's like broadcasting your conversion over the radio! If you are going to use one, get a digital one. The digital wireless phones transmits from the headset to the base in a digital method. Many of them come with scramblers and descamblers. This scrambles the info going from the baser to the headset. The other feature to look for is what is called spread spectrum. Spread spectrum sends data at one frequency and receives on another. Using these features and secure wireless phones will prevent most eavesdropping except for diplomatic level eavesdroppers. If you are at that level, don't discuss anything on the telephone at all--either a wired phone or wireless one.

Telephone Lie Detection

Tip Eleven:
Did you know you can turn your computer into a live lie detector when on the telephone? Truster software will do live analysis or analysis from tape recorders. For information on this unique software, go to:

Truster Telephone Lie Detection

Educating Yourself About Your Local Telephone Company Options!

Tip Twelve:
Want a huge and free education about the options you have with your local telephone service? Read the front pages of your local telephone directory. You will get a huge education about what you can use and I guarantee you will find something useful.

Blocking Call Waiting Beeps

Tip Thirteen:
Block incoming calls when you are on an important call. Many investigators these days use call waiting. Call waiting gives a little beep when another call in coming in and you are on the phone. This can be annoying when you are doing an important interview and will sometimes disconnect you when you are using the line on a modem or fax. By simply dialing "*9" before you make the call, you block call waiting. Any caller will get a busy signal.

Installing A Special Code For Callers To Make Your Phone Ring

Tip Fourteen:
Did you know you can filter out unwanted called with a new phone called The Call Filter Phone? When your number is dialed, the caller is asked to input a special security phone to make the phone ring. Without the code, the phone will not even ring. It's a great aid for a special phone line you only want a limited number of people to have access to. For more information, see:

Call Filter Phone

Quick-Check Telephone Tampering Tip!

Tip Fifteen:
Want to be able to quickly check to see if you phone has been tampered with? It's easy! Use A UV marketing pen on the screw heads of both your telephone and your telephone jack plate. Simple mark the location of the screw heads and check them with a UV light. If the screw head does not line up with your mark, you know someone has opened either your telephone or your jack outlet plate. You will find a selection of UV lights and marking pens at:

UV Lights And Marking Pens


Know The Number You Are Dialing From

Tip Sixteen:
These are known as ANAC numbers which are used by telephone repair people. Here are some national ones certainly reported. 800-444-4444, 888-324-8686, 800-444-3333, 800-727-5207, 800-555-1160.

Headset Telephone Recording Patchcord

Tip Seventeen:
On multi-line phones, investigators are often frustrated that they can not use a conventional telephone recording patchcord to record their investigative interviews. This problem is completely solved with the Headset Telephone Recording Pathcord. You will find a review of it at:

Handset Telephone Recording Control


State-By-State Telephone Recording Laws

Tip Eighteen:
When recording telephone conversations, it's very important for you to know and understand which states permit one party consent. One party consent means that one party to the telephone conversation has to have knowledge and give consent to a recording (you!). In States that do not permit one party recording, the other party needs to be advised and give their consent to a recording. You will find a detailed state-by-state listing of this at:

State-By-State One/Two Party Telephone Recording Law

You will also find a complete online handbook on this subject you can use for free at:

A Practical Guide to Taping Phone Calls And In-Person
Conversations in the 50 States and D.C.

Answering Your Phone Without Even Being There!

Tip Nineteen:
One and two man investigative offices are often in the field performing investigations. However, you need a way to answer your phone anywhere and anytime and need to do it 24 hours a day seven days a week. This can be accomplished with your telephone company call forwarding services. When in the field, you can forward your calls to your cell phone. When at home, you can have your office phone forwarded to your home. It's important to answer your phone with a live person so you don't miss any important new case assignments or new clients so do this!

Lifelong Answering Machines

Tip Twenty:
In my lifetime, I bet I have purchased a dozen answering machines. The problem is, after a while they break down. Almost all telephone services have what they call CallNotes. For a small fee, they act as your automated answering service for you. Check it out with your local telephone company.

Log And Manage Outgoing And Incoming Telephone Calls From Any Phone

Tip Twenty-One:
You can now obtain inexpensive equipment that logs and manages incoming and outgoing dialed telephone numbers with small telephone managers that plug right into your phone system. The Phone Manager logs and manages outgoing dialed numbers and the Two Way Information Manager logs and manages both incoming and outgoing numbers. For more information see:

Phone Managers/Loggers

Recording Calls From Your Cell Phone

Tip Twenty-Two:
Recording calls from your cell phone seems problemistic but here is your answer for the solution. Obtain any compact tape recorder with an external mic jack. Purchase a small amplified mic that will fit in your ear. Place the mic in your ear, turn the tape recorder on and dial the number. When you place the cell phone up to your ear, you will record the call. For information on various types of tape recorder mics see:

Specialized Microphones

Change Your Voice On The Phone

With a number of different types of voice changers on the market today, it's easy to change your voice when on the phone. Some of these voice changers make you sound digital but the better ones tend to let you find one or two settings that work well. For more information, see the following reviews:

Telephone Voice Changers


New Generation Digital Telephone Recording

Tip Twenty-Four:
Did you know tape recorders like everything else is going digital? The advantage is you can keep your recordings on your computer and use various types of software to enhance the audio with simple audio software. You can now keep your recorded investigative interviews that tape place either by telephone or in-person in a digital form and deliver them to your client on a disk or CD. For more information on digital tape recorders see these reviews:

20 Hour Micro Digital Recorder

10 Hour Micro Digital Recorder


Portable Telephone Scrambling Keeps Telephone Conversations
Confidential And Impresses Your Important Client!

Tip Twenty-Five:
By obtaining a set of portable telephone scramblers, you can keep two telephone conversations VERY private! Not matter what kind of eavesdropping is taking place, portable telephone scramblers will only allow communication to be understood by the sender and the receiver who both must have the scrambler. This type of covert communication over the telephone line is highly impressive with your important client and tells him or her that you are concerned about the confidential nature of the case. For more information on portable telephone scramblers that simply attach to the headset of a phone, see:


Portable Voice Scramblers

With all that said, I hope I have given you an education and a better understanding on how to make full use of the private investigator's number one weapon, the telephone!

Copyright: 2001, Ralph D. Thomas
All rights Reserved

Investigative Associations and newsletters have blanket permission to use this article without modification.