"'A trial court should not entertain, let alone initiate, communications with individual jurors except in open court, with prior notification to counsel. ' The prohibition against ex parte communications is designed to ensure that the defendant has '"an adequate opportunity to evaluate the propriety of a proposed judicial response in order to pose an objection...."' 'Although such communications violate a defendant's right to be present, and represented by counsel, at all critical stages of his trial, and thus constitute federal constitutional error, reversal is not required where the error can be demonstrated harmless beyond a reasonable doubt.' " (People v. Clark (2011) 52 Cal.4th 856 at p. 987.) "'Not every communication between the judge and jury constitutes a critical stage of trial,'" however. (Ibid.) A trial court, for example, may properly engage in ex parte communications for scheduling or administrative purposes. In Clark, the court answered telephone calls from two different jurors who called about the scheduling of the penalty phase of trial. The trial court described the communications as "brief and nonsubstantive" and "'just taking a message for administrative purposes.'" In those circumstances, our Supreme Court concluded that "the trial judge did not err when he spoke briefly to these jurors outside the presence of defendant and his counsel." (Clark, supra, 52 Cal.4th at p. 987.)