A method of assigning frequencies in a cellular telephone system in which a first group of the available frequencies is assigned to a first cell, and then distinct groups are assigned to adjacent cells, leaving at least one distinct group of frequencies free for later re-use. This system is applied to each cell in the system, so that for any cell, it and its adjacent cells do not use all of the frequencies in the system. For a first stage of cell splitting, frequencies are assigned from at least one non-adjacent cell (using the frequency re-use groups) to at least one part of the cell being split, while maintaining coverage of the cell from the same cell site. In a further stage of cell splitting in which there are adjacent first and second sets of three co-located end radiated cells, each radiated by directional antennas at first and second cell sites respectively, the cells are split by: locating a third cell site at about the mid-day point between the first and second cell sites; and radiating at least a third cell from the third cell site. An example is given based on 9 cells with sites arranged for end radiation of 3 cells from one site, thus reducing the number of cell sites. At each site the 3 co-located cells use frequency groups spaced to give protection against adjacent channel interference. The use of end radiated cells allows for less co-channel interference, as well as providing for a more distinct handoff between cells.