Many IR mark owners will not even know that Oman can be covered by an IR. Since the Oman trademark office is not well established (yet), the provisional refusals sent to WIPO usually do not meet the 18-months deadline. In this case WIPO informs the IR mark owner that the authorities in Oman rejected the mark, but this has no legal effect, since the provisional refusal objection was too late. Also other trademark offices in Arabian countries or in Africa are not fast enough to meet the 18-months deadline. Since these legal systems, e.g. in Oman, are not very well developed, it might be nevertheless be recommendable to file a response to the objections, since at least local counsel in these countries argue that a “too late objection” raised by, e.g., the Oman trademark office may not be relevant for WIPO, but will still be relevant for the national authorities in the respective country.
In some trademark systems, IR designations may formally be accepted, since the 18-months deadline has not been met, but nevertheless a response should be filed in order to get an enforceable trademark in the country. This should be checked by local counsel.