Glasses in the binary system xNa(2)P(2)O(6)-(1-x)Na2Te2O5 have been synthesised for 0 less than or equal to x less than or equal to 1. For all compositions, the glasses are transparent and appear homogeneous. Nevertheless for compositions near x = 0.4 glasses seem to be heterogeneous on SEM observations. Glass transition temperatures for all the compositions are between 220 and 310 degrees C. Conductivity data have been obtained using impedance techniques in the 100-250 degrees C temperature range. The sigma T product obeys an Arrhenius relationship with a composition-independent pre-exponential term A. The value of log A approximate to 4.8 in agreement with an indirect interstitial mechanism model for sodium cation migration. Isothermal conductivity curves with x show a maximum in the ionic conductivity. This mixed network former effect may be justified by assuming an endothermic mixture between sodium phosphate and sodium tellurate.