I have a locally issued UnionPay card debt card from CMB and SPD banks (as I more of less live in China), and I use the PIN there. For those that have been to China, and those going their soon, using a PIN is "normal" procedure. You might well notice that other customers at the establishment you are visiting will largely have "unsigned" UnionPay cards. Some people (not me) have locally issued cards (sometimes debit, sometimes credit) that have two or more liveries on it, one being UnionPay, and the other being Amex, MasterCard, and Visa (and while I have not seen them, perhaps Discover and others as well). I *assume* these are processed as UnionPay transactions in China, and under the other livery outside of China (although, UnionPay is reasonably popular in the region outside of China, such as in Hong Kong and Singapore).

On the rare occasion I find someone that will take my Amex, Visa, Mastercard, or Discover, the merchant will also ask me for my "mi ma" (PIN). I say "mei you mi ma" (no pin), and the transaction will either fail or get approved. I have a feeling that sometimes the reason is the merchant does not take my "foreign" plastic, or that the cashier does not know how to process non-UnionPay cards, as the overwhelming vast majority of all plastic in China is UnionPay.

In China, price sensitivity is very high with very low profit margins. This is in part why I think "foreign" cards are not accepted, as these cards take a percentage of the transaction (in part to help fund all the wonderful "points" and "miles" FT members are drawn to), while a UnionPay transaction seems to work as a debit card transaction with a small fee paid by the merchanct (I am guessing no more than the equivalent of USD$ 0.05) per transaction. Where you find "international" cards accepted, these are relatively "luxury" establishments that cater to ex-pats, visitors, or the well healed locals, and have a big enough profit margin that they can afford to pay a few percentage points of the sale to a financial institution. A simple restaurant or hotel likely will not take non-UnionPay cards, while a Four star or better hotel or a Western branded retail outlet (like Apple) will. Assume it is "cash only" unless you know otherwise.

I know that when you buy airplane tickets over the phone or online from a Chinese airline or agent (Chinese based website or call centre), they want to physically see your plastic before the sale is finalized, mostly so they can capture the PIN. Either you will be required to stop by their offices, or someone will come to you to deliver your "tickets" (including e-tickets) so they can get a swipe of the card as well as a PIN, or your cash). Sounds teriblle in efficient, but it works for them, as a couriers salary for a year is a lot less than a single fraudulent charge. Perhaps for international airlines and flights, they will let you sign a credit card. The courier will come armed with a mobile POS terminal. If you buy from a non-Chinese website, you can use your plastic as normally would if you were outside of China, with no face to face interaction.

At the end of the day, don't expect your credit cards to be taken anywhere other than a luxury hotel, and even then, I would verify in advance. If you are planning on being in China for any length of time, it is quite easy to open a Chinese bank account (esp. if a bilingual friend can help you) and many banks ATMs will dispense cash using your bank debit cards. Most big banks will take most cards (debit and credit), but some smaller banks will only take debit cards that have six digit PINs (in the US, the norm is for cards to have four digit PINs). As my US issued debit cards all have four digit PINs, I have to plan my visits to ATMs a bit in advance to find a compatible ATM, esp. if it is not a large city like Beijing and Shanghai.