Systems and methods are provided for communicating data over a subscriber loop using a modem. One such method includes: transmitting data on the loop in a first frequency band; sensing an indication that simultaneous transmission on the loop in a POTS frequency band is imminent; and adjusting transmit power in the first band, in response to the sensing step. One such system includes an input/output connection in communication with the loop, a processor operable in at least two states, a means for sensing demand for simultaneous usage of the loop, and a means for controlling the state. The first state is characterized by a first transmit power spectrum in the first band. The second state is characterized by a second transmit power spectrum in the first band, reduced relative to the first spectrum. Upon sensing demand, the control means causes the processor to operate in the second state.