Determining the transport demand is essential to develop models for trip planning. Until now, the most common way to estimate OD matrices is surveys in the field. In spite of the quality of results, this method is long, expensive, and sometime impossible to apply. Mobiles phone technologies provide new tools to investigate the travel behaviours of people. However, validity and reliability of these data for flow estimation should be assessed. In the paper, we propose a comparative analysis between OD matrices obtained from a commonly used traditional survey and mobile phone data analysis. Both trip surveys have been independently conducted at the same time and at the same point of the road network. Representativeness and variability of key indicators are studied. Similarities of trip distributions have been searched among OD relationships. Advantages and limitations about using GSM mobile tracking for trip surveys are then discussed. This novel method is concluded to be a promising alternative or addition to traditional survey protocols, but further developments are still needed.