If you are using China Mobile (CMCC), you can try the below methods to cut down on your Mobile bills especially for overseas calls! 

1) Within Shanghai

  If call directly using Mobile to Overseas, it will cost you RMB0.07/6secs. Incoming call free.

  Try This:

  - For out-going calls –> Dial 17951 + 00 (for international calls) + Country Code + Number

  - It only cost you RMB0.20/min

  - Incoming call free

2) Outside Shanghai

  If you call from overseas, it will cost you RMB0.6/min (Roaming) + RMB0.07/6sec. Incoming call charges RMB0.30/min.

  Try This:

  - For out-going calls –> Dial 12593 + 00 (for international calls) + Country Code + Number

  - It will cost you RMB0.39/min.

  - Incoming call charges RMB0.30/min

Hope it helps!