The Senate and the House of Representative passed the Truth in Caller ID Act, 2010 that amends the Communication Act of 1934 to effectively prohibits any caller ID spoofing. The Act prohibits the provision of deceptive caller ID information by making it illegal to “transmit misleading or inaccurate caller ID information.” The law, like most others, does not apply to “lawfully authorized investigative, protective, or investigative” agencies. The requirements for transmission of caller ID information have not been altered, meaning that you could lawfully block the outgoing caller ID information.
The law applies to “any real time voice communications service, regardless of the technology or network utilized”. Thus, this should affect all communication services, including mobiles, landlines, and even VoIP.