A system and method for handshaking multiple xDSL technologies is provided. More particularly, the present invention provides a means for new xDSL technologies such as VDSL to negotiate usage of bidirectional frequencies while maintaining backward compatibility with legacy, i.e. non-VDSL modems. In an embodiment, a central office modem configured to operate using VDSL technology provides a modified signal to a remotely located modem. The modified signal provides capability indicators to the remotely located modem that indicate the central office modem is able to use the VDSL bidirectional frequencies. However, the modified signal also maintains sufficiently similar characteristics to traditional capability indicators so that it can be interpreted by legacy modems.