Systems and methods for selectively enabling Robust Header Compression (RoHC) for Voice over Internet Protocol (VoIP) calls in a cellular communications network are disclosed. In one embodiment, a data radio bearer for a VoIP call is established between a base station and a mobile terminal. During the VoIP call, a radio frequency parameter for the data radio bearer is monitored. When the radio frequency parameter for the data radio bearer satisfies a predefined coverage-based condition, the base station enables RoHC for the VoIP call. In one preferred embodiment, the radio frequency parameter is a Signal-to-Interference-plus-Noise Ratio (SINR) for the data radio bearer for the VoIP call, and the predefined coverage-based condition is a predefined SINR threshold below which the base station enables RoHC. By enabling RoHC in this manner, RoHC resources are selectively made available for those VoIP calls that will benefit most from increased cell coverage provided by RoHC.