This study approaches teachers' identity development from a dialogical viewpoint, focusing on teachers' voices in a training course context about critical incidents (CIs) in teaching. The training course entailed the analysis and reflection of 15 CIs in online teaching from 12 online university teachers. The study's empirical element was 328 written utterances voiced from participants in the virtual campus throughout the course. An analytical framework based on different types of teachers' positions in teaching and a deductive content analysis approach were used to identify different types of teachers' voices about CIs in teaching. The results showed that four types of teachers' voices dominated the teachers' discourses in CIs: the voices about the "classroom CIs management" and the "teaching and learning processes" (voices on the educational practice) and the voices about the "teacher's roles" and "professional learning" (voices on the teacher himself/herself).