Resident Labour Market Test

I am currently employed as procurement officer and a position within procurement has become available which will result in change of job title but the SOC code will remain same which means I donot have to make a fresh application for sponsorship. ( if this is incorrect- please advise).

However, my query is related to requirement of Resident Labour Market Test i.e. to justify considering selection of non-EU/UK residents , is it necessary that the employer must advertise the job for 28 days ?

OR

The 28 day rule does not apply because an existing employee on Tier 2 might be selected - if so for how many days the job must be advertised ?

Thanks in advance to all who will take out time to response.