Hundreds of mobile towers in Pakistan’s southern Sindh province stopped transmitting during a July heatwave while their control systems continued to report them as available, according to research published on Thursday. The failure left an estimated 3.8 million customers with unreliable service, including people in parts of Hyderabad and the surrounding districts.
The paper, published by the Journal of Applied Network Engineering, examined anonymised operating data from two carriers covering 7,420 sites. Researchers identified 842 towers that lost radio service for more than 30 minutes; the network dashboards marked 1,106 sites as available during overlapping periods. On 17 July, temperatures in parts of the region reached 49.2°C (120.6°F).
When the radios went silent
The researchers say a power-saving system reduced radio output when equipment cabinets overheated. But its cloud controller counted a digital “heartbeat” from the site’s control unit as proof that the radio itself was transmitting. “The dashboard showed a green light while the service had disappeared on the ground,” said lead author Jonathan Salam, a telecom engineer at the fictional Nayaabad Institute of Digital Systems.
The system was checking whether the tower could speak to its controller, not whether anyone could use the network.
Jonathan Salam, telecom engineer
The power manager was made by Avelon Logic, a fictional software supplier whose founder Elisa Holmgren described its system as “self-correcting” at a product launch two years ago. The paper does not allege that the company caused the heatwave or knowingly concealed outages; it argues that the software’s definition of “available” was too narrow for extreme heat. Avelon Logic did not respond to questions by publication time.
In Hyderabad, interruptions left some residents unable to complete mobile payments or reach online booking services. Rangga Dongoran, who runs a small pharmacy near the city’s bus depot, said his payment terminal repeatedly lost its connection during the hottest afternoon. “People kept trying their cards, then had to come back later,” he said. “The signal bars on my phone were still there.”
A deadline for the carriers
Pakistan’s Digital Communications Authority ordered mobile operators to test whether their dashboards match live radio signals and to submit corrective plans by 30 October. Its order also requires carriers to publish outage figures during heat emergencies. The agency has not said whether operators will face penalties if later checks uncover further discrepancies.
One carrier, SaharLink, said its network remained available in most affected areas and that it was reviewing the paper’s findings. Spokesperson Leo Watson said the company would add checks that test “actual radio performance, not only equipment status”. The researchers say the gap matters because emergency services and residents may trust a coverage map that no longer reflects the signal on the street.
Salam said the findings should prompt operators to test their systems in real heat, rather than rely on laboratory thresholds set for cooler conditions. Two carriers have told the regulator they plan to spend 4.5 billion rupees (about €14 million) on additional cooling and monitoring equipment by March 2027. The paper warns that extra hardware alone will not fix software that mistakes a live control unit for a live mobile service.
