A party desiring to take the deposition of any person upon oral examination shall give reasonable notice of not less than three days in writing to the agency and all parties. The notice shall state the time and place for taking the deposition, the name and address of each person to be examined, if known, and if the name is not known, a general description sufficient to identify the person or the particular class or group to which the person belongs. On motion of a party upon whom the notice is served, the agency may for cause shown, enlarge or shorten the time. If the parties so stipulate in writing, depositions may be taken before any person, at any time or place, upon any notice and in any manner and when so taken may be used as other depositions.