The large bandwidth and low power level of ultra- wide-band make it susceptible to interference. Especially in a cell phone the interference levels are very high. Therefore cell phone integration of UWB receivers requires strong interference suppression. In this paper we use realistic models of interferers present in a cell phone. These models are used to derive the required detection time to reliably estimate the interference power. The needed detection time is found in unused medium access slots. A novel combined analog and digital suppression approach is used for interference suppression, only the combination provides sufficient suppression. We use system simulations to optimize the performance of the interference detector and to show that the interference tolerance can be improved by 36 dB.