Caught with my phone during an exam
My advice would be to be honest, not argumentative, and explain exactly what happened. 


I pulled the phone out with the intention to cheat.
I did not complete the cheat as I was caught in the attempt.
I turned the paper in immediately after being caught.
I have not habitually cheated.
I will accept whatever disciplinary outcome is assigned.


Maybe write this down and hand it in at the beginning of the meeting.

Accept the sanctions--not with a "crucify me" attitude, but phlegmatically.  Then, go and sin no more.