(b) Service of grand jurors in courts of the unified court system shall be for the duration of the term for which they have been drawn, unless sooner discharged; except that if the term of a grand jury has been extended by written order of the court having supervision of such grand jury, service shall continue until such grand jury has been discharged.
(c) For the purposes of this section, actual attendance shall include a juror's actual physical attendance wherein the court convenes or service by means of a telephone standby system whereby a juror shall remain available to report for jury service upon notification by means of telephone or other electronic communication.
(d) If the commissioner of jurors, after consultation with and concurrence of the district administrative judge or judges, or in the counties within the city of New York the deputy chief administrative judge, shall determine that sufficient numbers of potential jurors cannot be provided to any term or part of court the commissioner may extend such period of jury service for such additional period as may be necessary.