If you use a smart phone like Nokia, you can send a letter to Yi 'an, which can refuse to answer strange calls.
It must be a stranger who called you. You can try.
However, this method has many disadvantages. For example, if your classmates, teachers and friends change their numbers, you can't call in. And most importantly, your mobile phone must be a smart phone. If it's not a smartphone, don't try it.
So, either change the number or change the plane.