Dialing from New York to Shanghai:
Dial: 011 86 20  XXXX-XXXX
How the number is composed:
011 is the international prefix used to dial somewhere outside of U.S.A.
86 is the international code used to dial China.
20 is the local area or city code used to dial Shanghai.
XXXX-XXXX is the local number. Exchange X with your number.

Dialing  from Shanghai to New York:
Dial: 00 1 212 XXX-XXXX
How the number is composed:
00 is the international prefix used to dial somewhere outside of China.
1 is the international code used to dial to U.S.A.
212 is one of multiple city/area codes in use for New York.
XXX-XXXX is the local number. Exchange X with your number.