It's a phone translation service that makes travelling in China much easier. You sign up online for a certain number of minutes and then add credit when you run out. All you need is a mobile phone, which you can pass to anyone you need to speak to and they can interpret what you want to say. Best part is it runs 24 hours a day so it can be really useful when it's 3am and you've realised you've lost the address of the hotel you're staying in.
Using it with international roaming can be a bit pricey (as you're using a UK network's roaming rates) so I'd recommend getting a Chinese SIM card which means it's a local-rate call from anywhere in the country.
Last time I checked they were about to introduce a SIM card delivery service but might be worth checking first. We bought our SIM cards at Beijing airport.
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