This appears to be notification of intention to make a practical refusal decision, on the grounds the work involved in processing the request would substantially and unreasonably divert the resources of the agency from its other operations (s 24AA(1)(a)(i))

In order for an agency to do this, it must first engage in a request consultation process (the invitation to call the agency can be considered the start of this process). An agency may wish to state how an applicant is to consult with the contact person, such as by telephone. However it would be unreasonable not to adopt a flexible approach. It is important to note that the commencement of a request consultation process period stops the clock on the statutory deadline for FOI response (s 24AB(8)).

If an applicant contacts a contact officer during the consultation period, the contact officer must take reasonable steps to help them revise the request so that the practical refusal reason no longer exists (s 24AB(3)). For example, a contact officer should provide a breakdown of the time estimated for each step of the process, explain the difficulties the agency will have in dealing with the request and suggest what would be a reasonable request in the circumstances.

As the Information Commissioner FOI Guidelines state "It is nevertheless expected that an agency or minister, for the purpose of a request consultation process, will provide a breakdown of the time estimated for each stage in processing a request. An accurate estimate could be obtained through sampling a reasonable selection of the relevant files as an indication of the time that may be required for the decision-making process. A person with appropriate knowledge or expertise should assess the sample of the documents, looking at each document as if they were making a decision on access, including indicating the number of documents that could be released in an edited form. The assessment of the sample would provide an indication of the complexity of the potential decision, that is, the number of exemptions required, the topic and content of the documents, and the number of consultations required and effort required to contact third parties based on available contact details."

Hope this information is of assistance.