Is it illegal to record audio in the office using security cameras (with built-in microphones)?

I am in California and I am in charge of putting up security cameras in the office.

As long as the employee manual states that all communications and actions in the offices are SUBJECT to recording, that proves as warning enough.

Employers absolutely have the "right" to make sure their employees are working, not stealing corporate assets/services and to protect them company from an employees actions concerning outside forces.

Yes, it's called invasion of privacy.

Nope - not illegal.
However, you could have a lawsuit on your hands if you put them in the bathroom.

Video is fine in any state. The law varies from state to state on audio recording. In most states, one party consent is fine. That means that one party of the conversation must know that they are being recorded or listened to. It is illegal in ALL states to record or listen in on a conversation without the consent of at least one person involved in the conversation. To some degree, legal liability can be limited by posting signs that conversations and actions may be monitored by audio/video recording. Check with a local attorney before you do anything.

it's legal as long as the persons being recorded, are aware that they are being recorded, not just by camera but by sound as well.

No it is not illegal but don't put in other than public areas (ie bathrooms). It is almost never illegal to record a conversation in person or on the phone as long as you are a participating party in the conversation (ie you do not have to advise the other party/ies that they are being recorded). However, if you are not a participant in a conversation where a party/ies could not have known they were being recorded this is serendipitious and is probably illegal. A wire tap would fall in this category.

I dont think it is as long as everyone in the office is notified that they are being recorded. I worked at a retail buisness in VA and our sound and video was being recorded and I checked on that to see if it was legal or not and it was because we were told about it.

Yes it is also illegal to listen in unless prior consent is given by all parties. In California cellular and telephone conversations are also protected Recording would be an illlegal wiretap, a felony.
There are civil and criminal penalties.
see:
http://www.rtnda.org/resources/hiddencam...