I have been looking into this for a while... (Score 2, Informative)

I have done quite a bit of research into sending and receiving SMS to/from China in the past couple of years, partly because I lived out there until recently and mainly because needed to keep in contact with people in the UK, and now the reverse is true (so I can keep in touch with people there). As has been said in other replies this isn't down to censorship as some suggest but to do with peering agreements between networks. There are 2 major Chinese mobile networks - China Mobile (CM) and China Unicom (CU) - although this is changing soon or may have already. CU has a majority CDMA network, with a small (crappy reception) GSM network. CM is mainly GSM. The Chinese mobile needs to have international SMS / Calling enabled on their contract. This sounds obvious but is easily overlooked! I have tested with the following UK networks - O2, Voda (business contract) and Orange. Sending from China to UK CM > O2 CM > Voda CM > Orange all messages send from China, arrive in UK fairly soon after. CU > O2 CU > Orange all messages send and receive as above CU > Voda Couldn't get messages to arrive. Now, from the UK > China, things were a lot simpler. Orange > CU Orange > CM Voda > CM Messages send and are received. O2 > CU, CM Voda > CU No messages are received but report sent. I have contacted both the latter networks, and although they have roaming agreements with both Chinese networks (to allow voice calls on users travelling in the others region) they don't with SMS, so they can't guarantee a message sent will arrive (so they don't). Voda told me they have no plans for this (odd, since it sent fine to CM), O2 said they were trying to reach agreements in time for the Olympics (which after a quick test now they haven't managed). So in my experience, Orange in the UK and CM in China are the way to go. Orange actually have a PAYG tariff called "Camel" now which gives ridiculously cheap SMS and voice to China so it actually works out cheaper for me anyway. Hope that is useful!