Wireless is available in all major cities in China, but you have to know where to look. Refer to Place Descriptions for city-specific wireless hotspots in SW China. Or, take any phone line and plug it into your computer, and type in 16300 for the dial-up number, user name and password. Cost ~4 RMB/minute.
Your cell phone won't necessarily work in China (GSM 900). Find out, and if it does (any international cell phone works on GSM 900), make sure it's enabled for int'l roaming. Unless you've already got a good plan for making/receiving calls in China, the most economical option is simply buying a prepaid SIM card once you arrive China. If your mobile is locked against using a different SIM card, get it unlocked before coming over. Alternatively, all Chinese cities are littered with mobile phone stores - simply buy a new or 2nd hand one here.
China uses 220V (same as Israel and most European counties) with a frequency of 50Hz. If your country has a different voltage from China (the US uses 110 volts), you need a voltage converter for your appliances.
Note: there are 50- and 1600- watt converters. Most small electronics need a 50-watt converter - check the label on your appliance.
Dual voltage appliances and multi-voltage appliances eliminate the need for voltage converters. Dual voltage appliances (i.e., most travel hair dryers) can run on both 110 and 220 currents. Multi-voltage appliances (most laptops, for example) can run on voltages ranging from 110-240.
Note - you'll still need adapter plugs to fit the appliance into Chinese outlets.
These change the shape of a plug. If your country has a different outlet type from China, you need adapters so you can plug in your appliances. Chinese outlets take flat angled 3-pinned ("I" type), round 3-pinned, flat 2-pinned, or round 2-pinned.