If you do not own the cell phone this would be illegal. It is only legal for you to place cell phone monitoring program on a cell phone that you own, or for monitoring children, or for companies to monitor employees from company owned cell phones. According to the United States Federal register this type of monitoring is just and 100% legal. United states Electronics (261857199. Title 18, United States Code Section 2512 states basically that it is illegal for you to have a device that it's "primary" function is to "record" phone conversations without both parties consent. A normal cell phone that has had a monitoring program installed to it does not violate this statute due to the fact that the "primary" function of a normal fcc approved cell phone is to communicate.
Check out more info at enigma cellular dot com
Check out more info at enigma cellular dot com