中國的電信業由三大國有企業主導，分別是中國移動（China Mobile）、中國聯通（China Unicom）以及中國電信（China Telecom）。這三家皆提供全國性的移動通訊服務，涵蓋語音通話、行動數據（2G/3G/4G/5G）、固定寬頻與增值業務等，市場佔有率幾乎涵蓋中國所有用戶。雖然彼此競爭激烈，但在服務品質、收費模式、國際漫遊與對境外旅客的便利程度方面，各自仍有明顯差異。

中國移動是目前用戶最多、網路覆蓋最廣的電信業者。它在4G與5G建設方面投入巨大，幾乎全國大部分地區，包括偏遠鄉鎮也能穩定連線。對於需要長時間待在城市與郊區的人來說，中國移動提供的訊號穩定度與速度表現最好。不過其門號辦理程序相對嚴格，特別是針對境外人士，可能會要求更多身分驗證流程。而在價格方面，中國移動的資費略高，特別是針對短期用戶的方案，靈活度相對不足，國際漫遊收費偏高。

中國聯通則是三大業者中，最常被台灣與其他國際旅客選擇的對象，原因在於其SIM卡辦理相對方便，且對境外人士友好度較高。中國聯通提供多種短期數據方案與預付卡，部分門市甚至支援英文服務與網路預約開通。特別值得一提的是，它與多個國際電信商（包括台灣中華電信、遠傳與亞太）有合作漫遊協議，數據連線品質穩定，而且APN（接入點名稱）設定相容度高，台灣來的手機幾乎可以即插即用。在城市中的網路速度表現良好，不過若前往偏遠地區，其訊號穩定性可能略遜於中國移動。

中國電信則以高速寬頻與固網服務起家，行動網路方面則稍微落後於另外兩家，特別是在早期的3G時代因使用CDMA制式與其他制式不相容而影響口碑。然而，進入4G與5G時代後，中國電信已全面改採TDD-LTE與SA 5G架構，與中國移動和聯通接軌。它的訊號在南方城市普遍穩定，且近年價格競爭力上升，但針對旅客的即開即用服務仍不如聯通便利。不過若是停留時間較長、需要綁定家庭寬頻或辦理門號合約的外籍人士，中國電信的套餐相對多元且優惠。

總體而言，若是台灣旅客短期赴陸旅遊或商務考察，中國聯通通常是最便利、性價比最佳的選擇。不僅SIM卡取得容易，開通過程也較友善，且支援跨區漫遊，即使在不同城市間移動也不必更換門號。而對於有長期停留需求，或是需要長距離旅遊的人來說，中國移動因網路覆蓋力強仍具優勢。中國電信則較適合對價格敏感、且主要活動區域集中在南方城市如廣州、深圳或杭州的用戶。

需要注意的是，自2019年起，中國實施實名制管理，辦理門號必須出示護照並拍照建檔。因此無論選擇哪一家電信公司，建議前往正式營業廳辦理，以確保SIM卡能穩定使用並支援完整功能。此外，也可選擇在機場或部分便利商店購買旅遊專用卡，但仍需注意時效性與是否支援熱點分享等限制。

China's telecommunications industry is dominated by three major state-owned enterprises: China Mobile, China Unicom, and China Telecom. All three provide nationwide mobile communication services, including voice calls, mobile data (2G/3G/4G/5G), fixed broadband, and value-added services, collectively covering nearly the entire Chinese user base. Although competition among them is intense, they each have distinctive characteristics in terms of service quality, pricing models, international roaming, and convenience for foreign visitors.

China Mobile is the largest telecom provider by subscriber base and has the most extensive network coverage. It has invested heavily in 4G and 5G infrastructure, offering stable connections in most regions across the country, including remote and rural areas. For users who need reliable signal and speed both in cities and the countryside, China Mobile is often the best-performing choice. However, the process of obtaining a SIM card from China Mobile is relatively strict, especially for foreign nationals, as it may require more rigorous identity verification. In terms of pricing, its plans are slightly more expensive, and short-term packages tend to lack flexibility. International roaming charges are also comparatively high.

China Unicom is often the preferred option for travelers from Taiwan and other countries, due to its relatively foreigner-friendly SIM card acquisition process. It offers a variety of short-term data plans and prepaid options, and some retail stores even support English services and online activation. Notably, China Unicom has roaming agreements with several international telecom operators (including Chunghwa Telecom, Far EasTone, and Asia Pacific Telecom in Taiwan), resulting in stable data connections and high compatibility with APN (Access Point Name) settings, allowing Taiwanese phones to work out of the box. While its urban network performance is generally good, its signal stability in remote areas may lag behind that of China Mobile.

China Telecom initially gained prominence for its high-speed broadband and fixed-line services, but its mobile network development lagged behind the other two, especially during the 3G era when it used the CDMA standard, which was incompatible with most global devices. However, with the advent of 4G and 5G, China Telecom has fully adopted TDD-LTE and SA 5G standards, aligning with China Mobile and Unicom. Its mobile signal is stable in many southern cities, and its pricing has become increasingly competitive in recent years. That said, its convenience for tourists seeking instant activation is not as strong as that of China Unicom. Nonetheless, for long-term visitors or expatriates who need home broadband bundling or mobile contract options, China Telecom offers a wide range of affordable plans.

In summary, for Taiwanese travelers visiting mainland China for short-term tourism or business trips, China Unicom is usually the most convenient and cost-effective choice. It provides easy access to SIM cards, a user-friendly activation process, and nationwide roaming support, meaning users don’t need to switch numbers when moving between cities. For those with long-term stays or extensive travel plans across the country, China Mobile remains a strong contender due to its robust coverage. China Telecom, meanwhile, is a good option for budget-conscious users who mainly reside in southern cities such as Guangzhou, Shenzhen, or Hangzhou.

It's important to note that since 2019, China has implemented a real-name registration policy. SIM card purchasers must present a passport and have their photo taken for record-keeping. Therefore, regardless of the telecom provider, it is recommended to visit an official service center to ensure full functionality and stable usage of the SIM card. Travelers may also find tourist SIM cards available at airports or some convenience stores, but should be mindful of limitations such as data validity and whether hotspot sharing is supported.