There are many devices out there that can alter your voice like telephone scrambling equipment. These can attach to your telephone and with a switch can change your voice to up to eight different voices. The party you are calling will never know your identity.

These devices are very easy to install and use. Some of them are portable so you can bring them everywhere. This is just one device that you can add to your spy gear arsenal. Surveillance gadgets are a number one requirement for a private investigator. Cameras of all sorts should be available so that no action will be missed. Everything will be recorded and placed as evidence.