Text messages create particular evidential problems, because unlike emails and Instant Messenger conversations they cannot normally be printed out. This makes it difficult to present them in evidence.
The tribunal will not be impressed by being presented with a phone and asked to scroll through the messages.
The sensible course is to transcribe the messages onto a single document, with details of date, time, sender and recipient; then agree this with the respondent. If the respondent refuses to agree, the transcript and the phone can then be passed to the tribunal to confirm the accuracy of the record.