Outbound calls to a Chinese number had a failure rate of about 50% (failed with a couple of different error messages, can't quite remember what exactly they were anymore, although I remember thinking they didn't seem particularly relevant... like claiming the number dialed was busy even when it definitely wasn't, etc). Also sometimes the calls would go through but then disconnect immediately after I picked up and I would get billed for them. Basically, my experience calling China was that the service was totally unreliable and a bit expensive (by expensive I mean I was unhappy being billed for dropped calls).