Compatibility summary
You will need a travel adapter in Oman; plug types used there differ from Philippines.
Plug comparison
Philippines plug types: A B C
Oman plug types: G
There is no common plug type between Philippines (A B C) and Oman (G). You need a travel adapter.
Voltage comparison
Philippines: 220V, 60Hz
Oman: 230V, 50Hz
Voltage difference is within a range many devices tolerate; check your appliance label.