The glassy phases of SiO2, GeO2, B2O3, and P2O5 as well as selected pseudo-binary, pseudo-ternary, and pseudo-quaternary compositions of these compounds have been examined for glass transitions by differential thermal analysis (DTA) in the context of reflow of doped germanosilicate glasses. SiO2 does not exhibit a glass transition to temperatures above 1135 degrees C. GeO2 appears to exhibit a glass transition around 578 degrees C, while B2O3 appears to exhibit a glass transition in the range of 257-268 degrees C. Although the glass transition temperature of P2O5 could not be determined, the transition and melting behavior of the H, O, and O' phases have been reevaluated. Moreover, a new mechanism for conversion from H phase to O phase is presented. Namely, the melting of H phase followed by the spontaneous recrystallization of the resulting liquid to form the O phase was observed by DTA. Germanosilicate mixtures exhibited no glass transition, but the germanoborates' glass transition temperatures increased linearly with increasing GeO2 content. Examination of germanoborosilicates indicated that the addition of any germanosilicate composition to B2O3 causes a linear increase in glass transition temperature with total germanosilicate mole fraction, independent of the GeO2/SiO2 mole ratio. Pseudo-binary combinations of P2O5-B2O3 showed no thermal anomalies on heating or cooling cycles following an initial thermal cycle. However, pseudo-binary combinations of P2O5-GeO2 exhibited exotherms on cooling following initial heating cycles, which may indicate the occurrence of crystallizations that might interfere with reflow phenomena. Pseudo-quaternary combinations exhibited no thermal anomalies on heating or cooling.