have hong kong phone number begin with 8...

Yes. 011 is the international calling code, 852 is Hong Kong country code, then whatever phone number you have.

Phone number in HK starting with 1, 2, 3, 6, 7, 8, 9, in general speaking are in used,
there are 8 digit except starting from 1. Yours 89181233 is not a correct number!