It's easy to take your phone to China.
Most mobile phones can roam, or better still. Get yourself a Chinese SIM card.
Cards cost as little as 50 yuan - around US7 - but check to see what rate is charged, if it can be used nationwide, etc, as some cards charge a high flat rate for any call whether to your nearest hotel or a tour operator in the wild west.
Remember too, that you pay to receive calls - the same for others receiving your call.
So if you use Skype to call, it will cost them almost the equivalent of an international call.