①Service Provider 电信运营商
China Telecom is one of the biggest service providers here in China.
②SIM card 手机卡
There's no SIM card in your phone and that's why you can't use the mobile internet.
③Service plan 服务计划；套餐
Some handsets are free when you sign up to certain service plans.
④roam /roʊm/ v. 漫游
On my vacation I didn't realize that my phone was roaming. I paid a lot of money for each call.
Which service provider has a better coverage, China Telecom or China Mobile?
⑥top up 充值
I need to go to the shop and top up my mobile phone.
out of data/minutes 没流量了/没话费了
I am out of data.