In this day and age of gadgets and technology, it is easier than ever to bug someone's phone. If you suspect someone is listening in on your conversations, the only way to block a call-recording device is to find and remove it. With the right equipment this isn't hard to do, and only takes a few minutes to set up. This way, you will know your calls are always bug-free.
Check the phone line coming from the wall to your phone, and check the line coming into your house from the telephone box. You are looking for any electronic device attached to the line that is roughly the size of a deck of cards. If you find anything that looks out of place, simply remove it. This shouldn't require any tools.
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Buy a bug detector. These can be purchased from an online spy and gadget store. This will allow you to detect whether someone is listening in on your conversations. As of 2010, you can purchase one of these for about $200.
Detach the phone line from the phone and plug it into the bug detector. Then run the line from the bug detector into the phone. Turn the machine on and pick up the receiver. If there is a bug on the line, you will get a red light. If there is no bug you will get a green light. If a bug is detected, take the phone receiver apart. Bugs often are planted in the mouthpiece. You are looking for a small electrical transistor about the size of a quarter, with a speaker on it. If you find one remove it.
Check your cell phone's battery. If it seems to be draining very quickly it could be bugged and uploading the data from your phone calls to a remote server.
Check your cellphone between calls or when it has been turned off for awhile. If the phone is still hot to the touch, then it may be sending data.
Check to see if your phone flashes briefly when you are making a phone call. This often happens as your phone sends a message to the person monitoring your phone.
Bring your phone to a mobile shop. If you find any of these problems and you believe that you phone is bugged, then you will need to bring it to a professional to have the phone blanked and to get the software reinstalled. This will eliminate the bug. This should be done by a professional, as you can ruin your phone if you do this improperly.