A radio wave may suffer severe refractional effects at low elevations. Such effects will make the determination of the total electron content (TEC) inaccurate. Recently developed tomography techniques applied to ionospheric imaging would require accurate TEC measurements from overhead to the lowest possible elevation for a good reconstruction. It is, therefore, desirable to develop a method that will five accurate TEC measurements even at low elevation angles. One method that uses the difference of the TEC measured at two lower frequencies as a correction of the TEC measured at a higher frequency is proposed. The model study here shows the corrected TEC has a three-digit accuracy for all elevations. At low elevations the troposphere may also influence the radio path. The attempt here to extract the tropospheric information from the phase data shows only a moderate success for the atmospheric models studied.