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This study has observed and investigated random telegraph noise in the photoluminescence from InAs quantum dots in GaAs and InP quantum dots in GaInP. The dots are grown by the Stranski-Krastanow technique with a sufficiently low surface density that individual dots easily could be investigated. The luminescence from many single quantum dots, exhibiting switching between two levels, has been spectrally resolved as a function of time. The random telegraph noise is only observed in the presence of band filling. Results show no spectral shift of the emission in the different states. It is only the intensity, mainly for higher energy peaks that changes. The InAs quantum dots behave very similarly to InP/GaInP and InGaAs/GaAs quantum dots with respect to random telegraph noise. The similarities between the different systems argue for a common mechanism behind the blinking. Experiments are performed where the switching behaviour is changed in all the different systems supporting the idea that non-radiative defects are responsible.