China has three national networks:
 
• China Mobile 中国移动
• China Unicom 中国联通
• China Telecom 中国电信
 
All three are state-owned and controlled, with China Mobile the largest mobile provider in China (and of the world), followed by Unicom and then Telecom.
 
Compatibility of the three mobile providers:

* not compatible with many GSM-devices sold outside of China
 
China Mobile’s and China Unicom’s 2G (up to EDGE speed) are compatible with common GSM/2G phones (although US-models need quad-band). China Mobile’s 3G service is based on a weird Chinese-made TD-SCDMA standard, which unfortunately is not compatible with any phones from outside China. Again, if you brought your own phone from outside China, you will not be able to use 3G on China Mobile’s Network.
 
Only China Unicom’s 3G network is compatible with any unlocked phone that supports 2100 MHz 3G, which covers most modern smartphones in up to HSPA+ speed (max. 21.1 Mbit/s). China Telecom uses a CDMA network which is incompatible with all GSM-phones purchased outside China. Only a few CDMA devices from the US or Asia can adapt to their frequencies (for more details see China Telecom section below).
 
4G/LTE started in 2013 on China Mobile as TDD-LTE on 1900, 2300 and 2500 MHz, which is now starting to be used in other countries too. Certain phones like the iPhone 6 are usable on China Mobile's 4G network. China Unicom and China Telecom were given licenses for 1800 MHz 4G FDD-LTE which are compatible with most 4G phone models worldwide and are now already on the air in most cities.
 
Differences between the providers
 
Besides different prices and dataplans, the three companies vary in their market targets and services provided. Coverage wise if you plan to be outside tier one cities (SH, BJ, GZ, SZ), China mobile offers the best coverage of all three companies, covering the whole nation in 2G. However as 2G is essentially only EDGE speed which is around 320 kbp/s, it is useless for anything besides phone calls, text and instant messaging. Not holding a phone built for the Chinese market China Mobile's 2G is pretty useless for mobile internet or VoIP calls. For this, your only choice is China Unicom on 3G/4G, which still has a reasonable coverage.
 
China Mobile:
 
Without doubt, it has the best network in all provinces and is your first choice for voice and text as theses rates don’t differ so much among the providers. For data you will probably get only EDGE speed up to 384 kbit/s, but often slower. So desktop websites, VPN use (see above) or VoIP are not feasible on China Mobile on most GSM-devices. The iPhone 6/6+ (except those purchased from the major carriers in America) and certain Sony phones sold in Japan (Xperia ZL2 and Z3) support the 4G used by China Mobile, resulting in a much better data experience. In addition, the iPhone 6S and 6S+ will support TD-LTE on all models as the iPad Air 2 does, so if you are getting one, you can be assured of a good data experience on China Mobile.
 
You can check your balance at any time by sending an SMS with the text "ye" to the number 10086. If you have a data plan, you can send an SMS with the text "1091" to 10086, and you'll receive a reply stating how much data you've used and how much is remaining.
 
In most provinces like Shanghai or Beijing, new subscribers are now required to pick a base plan first, which is either a MZone, EasyOwn or a new 4G global plan. MZone plans include data allowances for mobile internet and in some provinces for WiFi hotspots with the SSID of "CMCC-WEB" around China, as well as generally nationwide free incoming calls and differ between regions. Their new 4G global plans (4G飞享套餐) all include both voice minutes and mobile data, with free incoming calls (e.g. valid in Beijing and Shanghai):
 
Overuse fees are 0.29 RMB per MB and having reached 60 RMB (at slightly above 200 MB) the rest of up to 1 GB is free. Note that this makes excess data very cheap at 60 RMB per GB, only capped at 500 RMB or 15 GB. In fact, it's cheaper for using data-only to buy a small package and use excess data instead
 
Unlike China Unicom, China Mobile has its own network in Hong Kong. However, this does not prevent them from selling their own roaming SIMs for mainland China out of Hong Kong. They come with some benefits, like bypassing the Great Firewall, skipping registration, and being able to top up with a foreign credit card. Additionally, China Mobile HK offers a bonus scheme for users, who reload online. However, their roaming SIMs are harder to find online, usually being limited to sales on eBay from third parties. If you are transiting Hong Kong on the way to China and have the time to step outside, there is a China Mobile kiosk just before security on the Departures level at HKG airport.
 
Pro tip: Additionally, if you are flying into China on Cathay Pacific or Dragonair, the data-only 4G/3G SIM is sold in-flight for a HK$8 discount off face value.
 
China Unicom:
 
China Unicom is the 2nd provider in the country and should be your preferred choice for data as it’s the only one that uses 3G UMTS up to HSPA+ speed on 2100 MHz like used in most other places in Asia, Europe or Australia (see Basics chapter). Their coverage is not as good as China Mobile’s but still reasonable and sufficient. They started FDD-LTE on 1800 MHz in some city centers in 2014 that is commonly used for LTE in other countries too. In 2015 the focused on their 4G expansion, rather than building up more 3G coverage. Still, it offers the widest compatibility with devices from other parts of Asia, Europe and Australia. It is recommended to buy their SIM cards in their shops or small mobile outlets with registration.
 
While it has an included monthly allowance for national data and outgoing calls and free incoming calls, it has very low overuse/default rates: 0.15 RMB per min for a call and only 60 RMB for 1 GB of data. A domestic SMS or MMS is at 0.1 RMB and an international SMS at 0.8 RMB. Their extra data rate is worth checking more closely: For 0-100 MB extra, they charge 30 RMB, for 100-200 MB extra 60 RMB in total. Beyond, there is no further charge from 200 MB to 1 GB. This scheme is repeated for every GB used additionally resulting in an overuse fee of no more than 60 RMB per GB. Extra data is capped at 15 GB and then shut off. So the larger combo packages only make sense, if you use a lot of domestic calls too. For more data better use the cheap default rate and don’t buy a larger pack. Especially, as for all higher monthly packages, they like to see a deposit, which is inconvenient, as it pays back only slowly in the following months.
 
You add credit to your China Unicom account and fees will be deducted, in advance, on the 1st day of each month. Keep in mind, though, that China Unicom’s billing cycle begins on the 1st day of each month regardless of the day on which you opened your account. This means that if you opened your account on May 29, you will be billed immediately a full month’s worth of charges for services between May 29 and 31, and a new billing cycle still begins on June 1.
 
For temporary visitors of China, 4G value packs also offer an option to switch the account to dormant mode when you leave the country. Once enabled, your account is required to stay dormant for a minimum of 3 billing months. Dormant mode gives you the option to preserve your +186 number in China while you are away from the country and reactivate your SIM immediately upon return. You dial 10010 to change these options, and customer service handles requests in English. When your account is dormant, a service fee of 5 RMB is deducted on the 1st day of each month.
 
Warning:
China Unicom (possibly all 3 major carriers), is getting very strict about prepaid for visitors. All 4G plans require you to cancel your plan to avoid being blacklisted. You can no longer just let your prepaid account reach zero balance and lapse on its own. If you leave the country without properly terminate your plan and account, you will not be able to re-register a new SIM/phone number on your subsequent visits to China. Termination of prepaid SIM/account require you showing up at the China Unicom corporate stores with the original ID used to registered the SIM. If you leave without properly terminating your account, the system will draw your balance through monthly plan deductions, until the balance reaches zero. The system will cancel and release your assigned phone number after 90 days after account reaches 0RMB. If you return to China at a later day and wish to register and activate another prepaid SIM/phone number, you will be required to pay the 90 days worth of monthly fee of the offending prepaid account, for the period when your account is sitting at zero balance prior to your number being released (if you did not properly terminate the account prior to leaving.) If you let your SIM/account lapse in this fashion multiple times (apparently this means 2 or more times), you will be blacklisted and not able to registered future SIMs through the normal proper channels. Cancellation of prepaid plan is only allowed if your account balance is 25 RMB or less, and it does not matter if you wish to forfeit the balance. Account termination must be done in person, and cannot be done over the phone, 10010.com website or online chat agents.
 
China Telecom:
 
China Telecom is the third and has the least people using their mobile plans. Telecom is mostly focused on providing landlines and internet connections. Often you will find bundles where the internet connect, landline comes with a mobile phone number attached often for discounted prices or free even. Depending on the packages it may be worth considering, however often it is simpler to just purchase them separately.
 
China Telecom uses CDMA (and thus EVDO for 3G) like (Sprint and Verizon) in the US and in a few other Asian countries, which is incompatible with GSM-devices (see above). Their reliance on R-UIMs instead of the traditional North American method of storing programming data in the phone means that from overseas, only a select few unlockable devices from the Japanese CDMA provider “au”, some Verizon phones from the US, and the latest generation of Verizon/Sprint-models with LTE and SIM/R-UIM slots are capable of using their network for voice and text. Older Verizon and most Sprint phones without card slots can be made to function on the network, however, this method is no longer available to visitors (purchasing mobile phone service online now requires real-time identity verification using a system that only functions with Chinese ID). Furthermore, China Telecom has the smallest network with a market share of around 14 %. As a consequence, it has lower-priced plans and a long-standing practice of offering significant amounts of bonus credit with new subscriptions to attract more customers. For customers with compatible phones or tablets, China Telecom will most likely be a better deal. Do note, however, that only Verizon and unlockable au LTE-capable CDMA devices will completely function upon insertion of a China Telecom R-UIM; older Android handsets will only function with voice and text without additional software modification. iPhone 5 and newer from Verizon and Nexus 5X/6P and iPhone 6 and newer from all carriers will also function with China Telecom without modification. iPad Air and newer will also function with China Telecom for data only. With these rates being much lower than on the two major players, you might also think of getting a CDMA USB-dongle or MiFi for data which is available for a few hundred RMBs, if you stay for longer in China. If you do not plan on leaving a major city and only need data, China Telecom runs an LTE network that is compatible with most devices sold overseas, even if they were made for GSM carriers.
 
 
 
Buying a SIM card
 
While it has become more difficult to get a local SIM card in recent days, the process is still relatively painless (but be prepared to wait if you go the official route) There are no regulations that you have to live in the country or province. Some vendors are trying to sell mostly China Mobile SIM cards on the street. If you do this, make sure the SIM works before leaving the vendor stand. While you can skip the tedious task of registration by doing this, you will not be able to receive any support after activation. Better go to small mobile shops or the official shops of the operators showing your passport and say “SIM Kaa” pointing at your device. Don’t expect anybody to speak English (you may be luckier if you are in a foreigner area of a big city). You may make a print copy in Chinese of the products which are featured on this site before going to the store.
 
The problem is recently, that most shops - even the small newsstands - only accept the machine-readable Chinese ID card. Foreign passports seem to be accepted only by the flagship stores of the providers (or at airports). While you may ask a Chinese to 'borrow' his ID card, you should know that behind the strict identification requirement is to track someone down in case of 'politically incorrect' use of the cell phone. What shops may do instead is sell you an unactivated SIM; this way, you can still enjoy the lower prices that third-party vendors are often able to get.
 
Start-up prices for the SIM cards can be very variable depending on the number. While a 8 in your number means good luck and an extra surcharge, a 4 in contrast is seen as bad luck and discounted. So prices are around 60 RMB for bad numbers up to 300 RMB for very lucky ones.
 
China's operators don't charge for new basic SIM cards (while a surcharge may be billed for a nano SIM). The minimum initial credit is 100 RMB and you have to choose a package for service, which starts at 8 RMB per month with no inclusive minutes or SMS. You can pay more (between 18 to 588 RMB per month) for a variety of combinations of minutes, SMS and data. Call costs vary depending on whether you are in or out of the province where you bought and registered the SIM card, and if you are out of province, then you also pay to receive calls unless you have a plan that includes it.
 
Data rates are generally low: all providers have lowered their default rate to 60 RMB per GB. This means that for data you can use their default rate. From 2015 all providers have also started to roll over unused data allowances in bundles over to the next month. The registration can lead to some paperwork but should be done in a couple of minutes even if you don’t speak the language. Their flagship stores are very recommended especially if someone speaks English there, as he/she can help you with problems using the service.
 
 On the other side, it’s not recommended to buy a SIM card at airports, as the prices tend to be higher there, although it will be easier to find an English speaker. Another option is to consider buying a Hong Kong-based SIM and roaming in the mainland with it. Both China Mobile and China Unicom sell dual-number SIMs in Hong Kong with very reasonably priced data packages that allow access to websites ordinarily not allowed (Great Firewall) as well as cheap voice calls and texts. Many of the Chinese issues below can be avoided by doing so (online top-up with home country credit/debit card means no one-province-only top-up voucher issues, all usage is priced at one national rate, no advertising texts) at the cost of somewhat higher prices on voice, text, and data (still well below roaming from most other countries). Normally, all three sizes of SIM cards are available. If not, someone will cut it to size for you.
 
Real name registration
 
A real name registration policy for mobile users in China was issued in 2010, requiring people to show their national identification card and complete a registration form when purchasing a new SIM card to activate mobile services. Started in 2013, all new mobile phone users have to register their real names in order to use any services. You might easily get a SIM card from a retail store on street, but you still have to go to the service point of the carrier for official registration and activation before using it.
 
Regional based SIM cards
 
All three providers are organized regionally. You get a SIM card for your province/town which is associated with its number like in the US or Russia. All calls are charged equally within the province, around 0.2 RMB per minute. And you are charged the same being called and calling out. Calls outside the province will have a surcharge again inbound and outbound, international (IDD) calls can be very expensive and often not enabled at all.
 
This national roaming exists not only for incoming calls but for data too. On many tariffs local and national data are distinguished. So try to buy your SIM at the place you intend to use it most or buy another SIM in the next province. Cheap foreign (IDD) calls can be made from landlines using special long-distance value cards called “IP cards” or using VoIP from your mobile if you have a stable 3G connection or a Wifi access. Be aware that an IP card costs about 20 to 25 CNY and has a credit of 100 CNY!
 
The regional organization of the mobile providers does mean that you have nationwide coverage, but topping up you SIM card outside of the province where you have bought it can be a formidable task. Recharge vouchers / top-up cards sold all over the country only work in the province where there are sold! This makes it very annoying for travelers to recharge their SIM cards.
 
So try to load enough credit in your “home” province, or you have to ask a local if he can help you. Of course online on the website of the provider or the platform of Taobao extra credit can be added from everywhere, but using a Chinese bank card only. Some travelers succeeded in topping up not by scratch cards sold all over but to look for the few agencies which provide direct / electronic top-up giving their phone number and paying in cash. Furthermore, there are reload agencies on the web, doing the top-up for a surcharge. Running out of credit is not a good idea, as your phone may be blocked for incoming calls too. This depends on the provider. China Mobile will allow you to run an overdraft. The amount varies depending on your payment history and how long you have been a customer with them. China Unicom may allow incoming calls even with a zero balance depending on your plan. If your plan allows it, you will receive a text when your balance reaches zero, notifying you of that fact. Your text messages may also be deleted if you have not stored them before in your phone.