We're dealing here with all the Gulf carriers of course (Emirates, Gulf Air, Qatar Airways, Egypt Air, Saudia, Etihad, Al Arabia, Yemenia... not to forget Oman Air).
In addition to these, we have some others from the neighboring countries (India, Pakistan, Iran, Bangladesh, Sri Lanka...). Some Asian carriers are as well benefiting from our service (Singapore Airlines, Cathay Pacific, Malaysian Airlines, Indonesian, Thai Airlines, Korean Air, Nepal Airlines...).
And finally, Oman being on one of the 2 or 3 main routes between Asia and Europe, we deal daily with most of the European airlines (British Airways, KLM, Air France, Alitalia, CSA...), including the ones from the main charter airlines groups (Britannia, Condor, LTU...).
Muscat airport is far behind others in the Gulf like Dubai, Abu Dhabi or Bahrain in terms of traffic but the Omani airspace is quite busy with the overflying one.
Muscat ACC (en-route control centre) uses 3 VHF (124.7 - 123.95 - 118.15 MHz) to render ATC service.
The sky has no limit...