Are you asking how to declare a mobile phone when going to Thailand? No need to declare, Thailand allows you to bring a mobile phone.

According to Thai customs policy, each passenger does not need to declare and can carry 1 mobile phone when entering and leaving the country. He can also carry 1 smart watch, 1 laptop, 1 tablet, and 1 mobile phone. Camera, 1 music player, 1 projector, 1 game console.

Notes when flying to Thailand: The number of mobile phones you carry cannot exceed the specified number. If you exceed the specified number, you may be taxed; the battery of your mobile phone must be full so that it can be turned on for inspection during inspection; prepare a valid Passports, visas, immigration cards and other documents for easy review before boarding.