ISSN No is one of the prerequisites for publishing a research journal, as no researcher would perhaps ever like to publish his/her research results in a research journal which does not have an ISSN No. The agencies involved in assigning ISSN No's can play a very substantial role and so can be played by other agencies, like CrossRef, etc. before assigning journals with DOI numbers.
Before assigning any standard numbers like ISSN or DOI, the agencies should ensure that all the members of the editorial board are genuine and due consent has been sought from all such board members, which these agencies should confirm from each board member individually. This should be followed by fulfilling other terms and conditions laid down, and if the same are fulfilled, then these agencies should go ahead with assigning such numbers.
Suggestions are welcome to curb the menace of predatory journals