You should be able to connect to the readyRead() signal. It might originate from QIODevice, which means you don’t see it in the QTcpSocket documentation.

QTcpSocket is a QAbstractSocket which is a QIODevice which has a readyRead() signal [doc.qt.nokia.com].

As a general rule: if you find that some method, signal, property… that you think should obviously be in a class isn’t in the documentation for that class, you should either browse the documentation of the superclasses, or just click the “List of all members, including inherited members” link. There is a good chance you’ll find what you are looking for in (abstract) base class.