I have a Motorola phone that I bought in Beijing and I want to bring it back to Taiwan. Does anyone know if a Taiwan IF card can be used in a mainland phone? Thanks in advance for your help. 
Yes before I got my nokia 6610 phone this week I used the one I got last august in shanghai all I needed to do was get a new sim. To be sure take it to an authorzied dealer and show them your phone they should be able to tell you if it is compaitable here. If u dont know chinese might want to bring someone who does.
Most of the mainland uses GSM phones still, so it should work fine. The only issue is that some providers lock the phone to your sim card because they sold the phone at a discount and don’t want you to reuse it. You can check this by trying out a friend’s sim card in your phone. If it works you are set. If it is locked and you have been a customer a while, your phone company will likely unlock it for you if you ask. If not, there’s still options. There’s websites, both free and for-pay that will generate an unlock code for you based on your serial number. There are also shops that will do this for a nominal fee.
There’s some networks in the mainland that use other technology, but if you know you have a sim card in the phone, it is probably GSM.