Oiler you can buy phone cards to use on the public phones over there, the airport will have several stalls selling them. The public phones there do NOT accept cash, at least they don't in Beijing, Tianjin and Guangzhou from my own experience.
Your girl can get you a sim card to use on your western phone if it supports the Chinese signal bands, not all do. I have have an all singing all dancing HTC phone that works everywhere. Only problem with a western phone is that it wont be able to display Chinese characters. I found it extremely useful to get one that did - several times i got lost or needed help and I just got my girl to text me the place in Chinese i was trying to get to and i could show it to a passer by or taxi driver. Got me out of a jam more than once let me tell you.
So i used my HTC phone in the end for its gps and translation software i installed and got a small China Mobile phone. She helped me with that, if you are not resident its a pain in the ass to get a sim card there unless you get one from a street vendor and they dont speak English in my experience.
For 400RMB my girl got me a nice little flip phone that came with a sim card on it that had 100RMB credit and could have its language switched to English , but still of course displayed the Chinese characters. I highly recommend this route.
The only other suggestion i have is this make sure there are credits left on it before you go..the package she got me was 26RMB a month subscription (under three euro a month ) but I called home a couple of times and the credit got used up quick so when i got back three months later the card was cancelled and they wouldn't give me a new one as it was issued in a different area (got the sim card in Guangzhou first visit and second visit was to Tianjin), a major pain in the ass.
In the end my girl just got me another sim from a street vendor, problem solved. I topped it up with another 100RMB before leaving so it will be fine for about another four months before getting cancelled..and I'll be back before then !
