Dublin District Court heard that Ms Conlon's messages had been intercepted over five-week period, from January 8 until February 11, 2010.
Yesterday the case was listed again but presiding Judge Ann Watkin could not deal with sentencing.
She said Judge Eamon O'Brien, who had heard the evidence and had found Doyle guilty, would have to finalise the matter.
Doyle was remanded on continuing bail; the date for her sentence hearing will be set in February.
During, the trial on June 28 last, Ms Conlon had told Judge O'Brien that she found out city councillors had listened to tapes of messages that had been left on her phone.
"A tape had been handed in by Councillor Mannix Flynn, with a message from my voice-mail," she had told the court, adding that she was "extremely upset".