What if someone who is aged 13 lies about their age and tells another person that they're like 20, and the other person happens to be 20 and they engage in cyber sex.

For your personal safety, do not ask for or give out your last name, address, phone number, email address, passwords or any of your Facebook, Skype, Yahoo, etc information to any person in this chat room.

Is cyber/phone sex legal or illegal if both people in each state are of the age of legal consent for real life sex?

Prominent politicians, business executives and Americans have seen their careers and lives derailed due to cybersex addiction. They were considered to be addictive in their cybersex use because they generally denied they had a problem; had made repeated efforts to decrease their online sexual activities; and continued going online despite poor academic or job performance, relationship difficulties, job loss, sexual harassment lawsuits, arrest, failed relationships, or other adverse consequences related to their cybersex use.

The Internet and the immediacy that it offers for sexual gratification has shaped our society more profoundly than any other media in history. These cybersex users spent at least eleven hours per week in online sexual pursuits.

Assuming she consents, can they legally have sexual intercourse?

As long as 16 is the age of consent in both states, the age gap does not matter. It doesn't matter if one is one day over the statutory age limit and the other is 100.

I had a feeling a prosecution would say that ignorance is no excuse for breaking the law...

With personal stories from porn addicts and significant others, professionals Robert Weiss and Jennifer Schneider offer direction, understanding, and hope to anyone sturggling with the devastating effects of porn and sexual betrayal on intimacy, relationships, family, career, and self respect. Approximately 1 percent of those identified as “cybersex addicts” in a follow-up analysis reported a lengthy history of sexual acting out (compulsive sexual activities) and sexually addictive behaviors such as anonymous sex, sex with prostitutes, and compulsive masturbation, that long preceded their discovery of sex on the Internet.

Alvin Cooper and associates of a 9,265 Internet users found that 8.5 percent were sexually compulsive or addicted.