In this contribution the subjective evaluation of three Text-To-Speech systems (two diphone and one allophone system) is reported in three'transmission conditions: standard telephone (PSTN) and GSM. The three TTS-systems realised three different texts: Travel information, Stock Exchange Reports and E-mail messages. The subjects had to carry out three tasks: a) to give preference judgements on the three TTS-systems and b) to rate the readings on 16 five-point scales. The rankorder on the scale of general quality was: Public Transport Stock Exchange E-mail reading, in both transmission conditions. The GSM-transmission tends to decrease the perceptual scores on a number of subjective scales, In the transliteration task significantly more errors were made in the GSM- condition than in the PSTN-condition. In both conditions less errors were made with the diphone TTS-systems than with the allophone system.