Disgruntled customer here. I signed up for the World Connect plan in April 2014, thinking it would cover all calls I made to people in China (I make regular calls to there for business and family) My wife went over to see her family, and like a good husband, I called her regularly, thinking the whole time World Connect would give me a preferred and affordable rate. I found out this was not the case when my wife received a text from ATT, stating we had $500 in overages. A huge unaffordable amount. ATT would not credit the charges, only doing a rerate that ended us with $350, an amount we cannot afford. Worse yet, their customer service has been a nightmare to get ahold of, with dropped calls and endless transfers. Previously ATT had been nice to work with, helping us with credits for our overseas travels when necessity demanded we use our phones to contact loved ones. This time, employees insinuated that I knew the charges were going to happen, and that they weren't going to let me hoodwink any credits out of them. That's especially hurtful, as I thought World Connect would be a proactive way to avoid the need for any more overseas charges. I was really wrong to trust in AT&T's extra services, and the huge charges mean I won't renew my contract and will sign with another provider.
TL;DR: World Connect only covers calls overseas to those with non-American phone lines, got a bunch of charges because of this, AT&T stuck me with hundreds of dollars in charges causing me to switch companies.