Section 27. The office of jury commissioner may summon additional grand and trial jurors to appear for juror service forthwith or at a time certain, with or without the right of postponement of juror service, with or without the opportunity to change the selection of the courthouse to which the juror has been assigned, in order to meet the urgent needs of the court. The office of jury commissioner shall employ whatever means of notice, including telephone notice, that is appropriate under the circumstances.