The background to, and current state of, the CEPHOS project is reviewed. This has the objective of producing uniform pan-European guidelines for numerical and experimental dosimetry procedures to evaluate the effect of mobile telephones on human users. Technical work packages within the project are focusing on test pieces (physical and software) to evaluate comparability of test procedures and electromagnetic modelling software in different laboratories. The test pieces are both canonical and realistic, and particularly novel work is being undertaken on the detailed modelling of handset antennas.