Iran blocked WhatsApp amid war with Israel

Amid the twelve-day war between Iran and Israel in June 2025, Iranian authorities urged residents to delete WhatsApp over concerns of data being shared with Israel. Meanwhile, WhatsApp users in Iran started reporting the blocking of WhatsApp.

OONI has reported on various forms of Internet censorship in Iran over the past decade. Instant messaging apps like Telegram, Facebook Messenger, and Signal have been blocked in Iran for years, and remain blocked to this date. Access to WhatsApp was blocked on 21st September 2022 (amid the Mahsa Amini protests), and the block remained in place for more than two years. Iran reportedly lifted the WhatsApp block on 24th December 2024, and this is corroborated by OONI data.

However, amid the conflict between Iran and Israel, OONI data shows signs of access to WhatsApp being interfered with in Iran again. Specifically, the OONI Probe testing of WhatsApp on multiple networks in Iran presented a large volume of anomalies between 15th June 2025 to 12th July 2025 (particularly in comparison to measurements collected in the weeks before and after these dates, most of which were successful), suggesting that access to WhatsApp may have been blocked on some networks in Iran.

The following chart aggregates OONI measurement coverage from the OONI Probe testing of WhatsApp on 48 local networks between 1st May 2025 to 31st July 2025.

As is evident from the above chart, there is a significant drop in OONI WhatsApp measurement coverage between 13th to 24th June 2025, which correlates precisely with the dates of the twelve-day war between Iran and Israel. Within this period, the timing of the availability and absence of OONI measurements further correlates with and corroborates the Internet disruptions findings observed in IODA and Cloudflare Radar data.

Specifically, between 13th to 18th June 2025, there is a significant drop in OONI measurement coverage in comparison to previous weeks, suggesting a potential Internet disruption. However, the presence of some OONI measurements during this period suggests that Iran did not experience a complete Internet blackout, as some OONI measurements were uploaded to the OONI collector during the period of the reported Internet blackout. The hypothesis of reduced Internet connectivity between 13th to 18th June 2025 (as inferred by OONI data above) correlates with the signals observed in IODA data.

Between 19th to 20th June 2025, there is almost complete absence of OONI measurements, suggesting the presence of a high severity Internet connectivity shutdown (which would have prevented OONI Probe users in Iran from submitting measurements for publication). This correlates with the timing of the near-total Internet connectivity shutdown observed in both IODA and Cloudflare Radar data. And similarly to these datasets, OONI measurements suggest that Internet connectivity was gradually restored from 21st June 2025, and that Internet traffic had recovered by 25th June 2025.

But beyond Internet connectivity disruptions, OONI data also suggests that ISPs resumed the blocking of WhatsApp during this period. The above chart illustrates that while most measurements from the OONI Probe testing of WhatsApp were previously successful (annotated in green), they presented a spike in anomalies (annotated in orange) between 15th June 2025 to 12th July 2025 – suggesting that access to WhatsApp may have been blocked on some networks in Iran during this period. This is further suggested by the fact that OONI data shows that WhatsApp was reachable in most countries globally during those dates, thereby excluding the hypothesis that the anomalies observed in Iran were the result of WhatsApp being down globally.

Disaggregating OONI WhatsApp measurements by tested network in Iran shows that the vast majority of anomalies were present on the MCI (AS197207) and TCI (AS58224) networks (which also received the largest measurement coverage), shared below.

It seems quite unlikely that the majority of these anomalies were caused by Internet connectivity disruptions and transient network failures, as the data from such anomalous measurements shows that many TCP connections to WhatsApp endpoints were successful. Instead, OONI data shows that the TLS handshakes for WhatsApp Web (web.whatsapp.com) and the WhatsApp registration service (v.whatsapp.net) failed, resulting in timeout errors.

OONI data suggests that access to WhatsApp may have been blocked by means of TLS interference as the TLS session times out after the ClientHello message, indicating SNI based filtering (informed by WhatsApp domains). This is consistent with the censorship methods known to be adopted by Internet Service Providers (ISPs) in Iran.

If you are in Iran, you can test WhatsApp and contribute more measurements by running OONI Probe.