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On August 10 and August 13, roughly 16 million people across northern and central Taiwan will pick up their phones and find that 4G and 5G data has been reduced to about 1% of normal capacity for 30 minutes — not because of a cyberattack or Chinese naval blockade, but because Taiwan's government is deliberately simulating exactly that. Video streaming, video calls, social media uploads, cloud-based apps, and large file transfers will become effectively unusable, according to Taiwan's Central News Agency. Voice calls, SMS messages, and Cell Broadcast Service emergency alerts will continue to function normally — and that distinction, it turns out, tells you nearly everything about the technical logic of what Taiwan is attempting.
The National Communications Commission (NCC) confirmed this week that 4G and 5G mobile data speeds will be throttled to approximately 1% of normal capacity during two 30-minute windows as part of the Urban Resilience All-Out Defense Mobilization Exercises, running concurrently with the annual Han Kuang 42 military drills from August 5 to 14, Minister of National Defense Wellington Koo told reporters. It is the first time any mandatory civilian bandwidth restriction has ever been imposed in Taiwan's history — a fact Taiwan's government has been notably deliberate about framing as a preparedness measure rather than a government power over civilian internet, even as it exercises exactly that power, Reuters reported.
Exactly What Will Stop Working — and What Will Not
The throttle will cover 14 cities and counties in two geographic phases: central Taiwan on August 10 (2:30–3:00 p.m. local time), including Taichung, Chiayi city and county, and Miaoli, Changhua, Nantou, and Yunlin counties; and northern Taiwan on August 13 at the same local hour, covering Taipei, New Taipei City, Keelung, Taoyuan, Hsinchu city and county, and Yilan County, according to Taipei Times reporting on the NCC's planning notice. Together, the affected regions are home to approximately 70% of Taiwan's population, Reuters confirmed.
At 1% of typical 4G or 5G throughput, a connection that normally delivers 50–100 Mbps of download capacity will drop to 0.5–1 Mbps. That is barely enough for low-quality voice-over-IP at degraded quality — but it is not enough for video streaming, real-time navigation that hasn't been downloaded offline, photo uploads, or any cloud-synchronization service. Officials from the NCC are explicitly recommending that residents download offline maps before the drill windows, reschedule any critical video meetings to fixed-line or Wi-Fi connections, and agree in advance on physical meeting locations and landline fallback contacts, Focus Taiwan reports.
Voice calls will be protected throughout. This is not a coincidence — it reflects how 4G and 5G networks technically separate voice and data traffic (see the technical mechanism section below). Emergency services, traffic signals, and ATMs will also be entirely unaffected, as they run on dedicated fixed-line or private wireless infrastructure that is architecturally separate from the consumer mobile data network, according to Focus Taiwan.
Southern Taiwan is entirely excluded from the exercise. The reason is unusually candid: the NCC's Secretary-General Wen Chun-yu confirmed that the southern urban resilience phase is scheduled during morning hours when the Taiwan Stock Exchange is open, and slowing mobile internet during active trading hours risks disrupting smartphone-based stock transactions, the Taipei Times reported. That single carve-out may be the most eloquent illustration in the entire episode of just how completely real-time economic infrastructure has become dependent on mobile data.
Why Taiwan Is Doing This — The Cable Cuts Behind the Drill
The bandwidth throttle is not a hypothetical preparation for a hypothetical war. Taiwan has already experienced, in miniature, exactly what a large-scale communications disruption looks like.
Since 2023, at least 11 documented incidents of suspected undersea cable sabotage have occurred around Taiwan, with Chinese-flagged or Chinese-linked vessels implicated in multiple cases, Al Jazeera reported in March 2025. In February 2023, two cables supplying Taiwan's Matsu Islands were severed, leaving residents without internet for more than 50 days while repair vessels were organized. In January 2025, the vessel Xingshun 39 — a Tanzanian-flagged ship controlled by a Hong Kong company and crewed by Chinese nationals — disabled its tracking system and dragged its anchor over the TPE cable north of Taipei, Just Security documented. A month later, the Hong Tai 58 severed the TPKM-3 cable connecting the Penghu Islands to Taiwan, the Global Taiwan Institute reported.
Taiwan has 15 submarine cables landing at seven shore stations — a concentrated, vulnerable architecture in which a determined adversary could produce island-wide communications degradation without firing a conventional weapon. The August bandwidth drill is designed to simulate what happens when that degradation occurs: how do citizens communicate, how do government agencies coordinate, and what backup systems actually work under pressure?
"We hope the current drills will not only involve central government agencies, but also help the public strengthen their own preparations for using different communication methods," a senior Taiwan security official told Reuters, pointing to the "spike in Chinese coast guard activities off Taiwan's Pacific coast" as operational context. Options range from landlines and fixed-line internet to walkie-talkies — technology that predates mobile data dependency entirely.
How the Throttle Actually Works: QoS Policies at the Radio Access Network
The technical mechanism behind this drill is specific enough to be worth understanding in detail, because it explains both what the drill can test and what its limits are.
In 4G LTE and 5G networks, all data traffic flows through a layered architecture. User devices connect wirelessly to base stations — called eNodeBs in 4G, gNodeBs in 5G — which in turn connect to a core network. Within that core network, a specialized function called the Policy and Charging Rules Function (PCRF in 4G; Policy Control Function, or PCF, in 5G) governs how much bandwidth each subscriber session is permitted to use. Carriers enforce bandwidth caps by pushing Quality of Service (QoS) profiles — essentially, speed limits — from the core network down to the base stations that serve those subscribers.
To throttle all users in Taiwan's 14 affected administrative regions to 1% of normal capacity, the NCC and participating carriers will configure QoS policy rules targeting all active subscriber sessions in those areas. The result: the Policy and Charging Rules Function will assign each data bearer a drastically reduced guaranteed bit rate, effectively capping throughput island-wide within the affected jurisdictions.
Voice calls survive this process for a specific reason. In 4G and 5G IMS (IP Multimedia Subsystem) architectures, voice calls use a separate bearer channel classified as a Guaranteed Bit Rate (GBR) bearer with QoS Class Identifier (QCI) 1 — the highest-priority class in the 3GPP specification. These bearers are protected from bandwidth throttling by design; carriers and regulators can cap data bearers without touching voice. In older networks that use circuit-switched fallback for voice (CSFB), the separation is even more complete.
Cell Broadcast Service emergency alerts work by a different mechanism entirely. CBS does not use the data plane at all — it transmits on the BCCH (Broadcast Control Channel) in 4G, a signaling channel that operates independently of user-plane data capacity. All compatible mobile devices in a geographic area receive CBS messages simultaneously without consuming any data bandwidth. This is why Cell Broadcast Service is the standard for emergency alerts globally: the U.S. Wireless Emergency Alert system, Japan's J-Alert, South Korea's equivalent, and the European Union's EU-Alert system all rely on it for the same reason — it works even when data networks are congested, failing, or deliberately throttled.
The NCC's stated goal of simulating "emergency measures such as disaster roaming and traffic prioritization" maps directly to this architecture: in a real invasion, earthquake, or cyberattack, mobile network congestion would emerge spontaneously as millions of users try to communicate simultaneously on damaged or overwhelmed infrastructure. The drill artificially replicates this condition under controlled, announced circumstances. What it cannot test is the population's behavior when the degradation is unexpected — but that is arguably the harder civil-resilience problem, and one that may require separate exercises to address.
Han Kuang 42: First Time Civil and Military Exercises Run Together
The bandwidth throttle is embedded within Han Kuang 42, Taiwan's 42nd iteration of the annual military exercises it has conducted since 1984. Han Kuang began as a conventional military readiness drill — live-fire maneuvers, computerized war games — intended to simulate Taiwan's response to a Chinese invasion, the Global Taiwan Institute's analysis of the 2025 exercises documents. The 41st iteration in 2025 was the longest on record at 10 days of continuous live-fire operations, involving more than 22,000 reservists and introducing fully unscripted free-play scenarios for the first time, USNI Proceedings reported in October 2025.
This year's iteration marks a structural expansion beyond military units: for the first time, the Urban Resilience Exercises are fully integrated with Han Kuang rather than run in parallel. The resilience exercises have also expanded from a single day to two days — one dedicated to tabletop war-game scenarios and a second to field application of those plans, the Taipei Times reported. Exercises will encompass civilian evacuations, underground medical operations, drone-based supply deliveries, medical evacuation logistics, joint transportation coordination, and cross-county support drills testing how neighboring jurisdictions can share resources when their own infrastructure is damaged.
The civil-military integration is deliberate doctrine, not administrative convenience. President Lai Ching-te has established a Whole-of-Society Defense Resilience Committee, which convenes quarterly with representatives from government agencies, industry, and civil society, and has defined five lines of effort: civil manpower training, emergency supplies, energy security, medical capacity, and — specifically — cyber and communications redundancy, the Council on Foreign Relations documented in April 2026. The bandwidth throttle drill falls squarely within that fifth pillar.
Taiwan's Drill Sets a Democratic Precedent — With Implications Beyond the Island
The NCC has been emphatic that what is happening in August is "not an internet shutdown" — and technically, that distinction has merit. Taiwan's exercise is announced weeks in advance, limited to 30-minute windows, scoped to data services only (voice and emergency services remain operational), and conducted transparently by a democratic government for publicly stated civil-defense purposes.
That said, Access Now's taxonomy of internet shutdowns — the most widely cited international framework for classifying government network interference — explicitly includes throttling as a form of shutdown, regardless of duration or stated intent. By that framework, Taiwan is conducting an internet shutdown. The distinction Taiwan's government draws — managed degradation, not blackout — is real and important, but it does not exist as a formally recognized category in current international human rights frameworks.
This matters not because Taiwan's exercise is wrongful — by nearly any proportionality test, a 30-minute, pre-announced, voice-protected throttle for civil-defense testing is defensible — but because Taiwan is creating a template. Officials have already cited Japan, South Korea, Singapore, and EU member states as conducting analogous disrupted-communications drills, the Taipei Times reported. If the "democratic managed degradation" framing becomes established practice among liberal democracies, it also becomes available as rhetorical cover for governments whose motives are less transparent. That is not an argument against the drill; it is an argument for the international community to establish clearer normative distinctions between a pre-announced civil-defense throttle and an authoritarian suppression tool — distinctions that do not yet formally exist.
Taiwan's defense ministry has said it will evaluate the August results before deciding whether to expand the exercise nationwide. If the drill proves effective at revealing gaps in public communication preparedness, nationwide implementation in future exercises appears likely.
What Residents and Businesses Should Do Before August 10
For anyone in northern or central Taiwan — or with business relationships that depend on mobile-connected counterparts in those regions — the practical preparation is straightforward:
Download offline maps now, before August 10. Navigation apps like Google Maps and Apple Maps allow offline map downloads; during the drill window, real-time map data will be unavailable over 4G or 5G. Any video meetings or real-time data-dependent transactions scheduled between 2:30 and 3:00 p.m. local time on August 10 (central Taiwan) or August 13 (northern Taiwan) should be moved to fixed-line or Wi-Fi connections, or rescheduled entirely. Voice calls and SMS will work normally. Online orders, identity document uploads, and any real-time trading conducted exclusively over a mobile connection may be disrupted, Focus Taiwan advises.
No subscriber refunds or fee reductions will be offered, as voice and SMS services remain fully operational throughout each window. The NCC will notify residents via Cell Broadcast Service alerts, television news tickers, and radio announcements in advance of and during the drill.
For anyone conducting stock transactions, the stock market exemption applies only to southern Taiwan (which is excluded from the drill to protect trading infrastructure). Northern and central Taiwan residents who trade via mobile 4G or 5G connections should use fixed-line internet access or Wi-Fi during those windows.
Frequently Asked Questions
Is Taiwan's August drill actually an internet shutdown?
Taiwan's government says no — and technically, data connections will not be cut, voice calls will continue to work, and emergency services remain fully functional. But Access Now's internationally recognized taxonomy of internet shutdowns classifies throttling as a form of shutdown, because the practical effect on data-dependent services is a near-total blockout. The real distinction is normative and procedural: Taiwan's exercise is pre-announced, time-limited, democratically authorized, and voice-protected. Whether that amounts to a meaningfully different category of government network intervention — or just a more transparent form of the same power — is a question international human rights frameworks have not yet formally resolved.
Why is southern Taiwan exempt from the bandwidth throttle while northern and central Taiwan are not?
Because the southern phase of the Urban Resilience Exercises is scheduled during morning hours when the Taiwan Stock Exchange is actively trading, and mobile data throttling during those hours risked disrupting real-time smartphone-based stock transactions. NCC Secretary-General Wen Chun-yu confirmed this exemption explicitly. The carve-out is arguably the drill's most revealing data point: even a temporary, government-announced bandwidth restriction carries measurable economic risk when financial markets depend on mobile connectivity.
What happens to voice calls, emergency services, and Cell Broadcast alerts during the throttle?
All three remain fully functional — and for specific technical reasons. Voice calls in 4G and 5G networks use a protected bearer channel classified with the highest Quality of Service priority (QCI 1 in 4G), which is architecturally shielded from data throttling. Emergency services use radio-based dispatch networks that do not rely on consumer mobile data. Cell Broadcast Service — the system that will notify residents during the drill itself — operates on a separate signaling channel (the Broadcast Control Channel) that is entirely independent of user-plane data traffic. It is the same technology underlying the U.S. Wireless Emergency Alert system and Japan's J-Alert.
Does Taiwan's drill set a precedent for other governments to throttle civilian internet under the guise of "resilience testing"?
This is the question the drill raises most sharply. Taiwan is among the freest internet environments in Asia (Freedom House, 2024), and its drill is transparently conducted with full advance notice and democratic authorization. But officials have already cited Japan, South Korea, Singapore, and EU states as conducting similar drills — and the "democratic managed degradation" framework, once normalized among liberal democracies, provides rhetorical cover that authoritarian governments can appropriate. No international standard currently distinguishes a pre-announced civil-defense throttle from a politically motivated suppression tool at the normative level. Taiwan's drill makes establishing that distinction more urgent.
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