November 16, 2025
Call me, maybe… hear everything?
Call Me Maybe: Eavesdropping encrypted LTE calls with ReVoLTE (2020)
Old LTE call snooping trick resurfaces—nerds impressed, skeptics yawn
TLDR: Researchers showed some LTE towers reused call encryption, letting crafty eavesdroppers decode parts of previous calls by ringing you afterward. The crowd calls it old news and impractical, while a few geeks say it's still a neat reminder that 'encrypted' doesn’t always mean safe
The research team behind ReVoLTE dropped a throwback shocker: some cell towers reused the same “lock” on back‑to‑back phone calls, meaning a crafty listener could call you right after and decode parts of your previous chat. It’s Voice over LTE (aka VoLTE), the system that carries most phone calls today, and the flaw appeared in 12 of 15 towers they tested. The team even demoed it and pointed to the USENIX Security Symposium (2020) for the full nerdy details, plus an app to spot vulnerable networks.
Cue the comment drama. One camp is fascinated—“old but still interesting,” cheered vxvrs—treating it like CSI: LTE. Another camp slammed the brakes: “(2019)” sneered stop50, dunking on the timeline. And the practicality police showed up fast: puppycodes called it “not worth the effort,” arguing there are easier ways to eavesdrop than replaying tower mistakes. Memes flew: “Call Me Maybe, then decrypt me,” “Press F to fix your base station,” and “encrypted, but make it optional.” The vibe? A split screen between privacy panic and the Meh Brigade. Still, the takeaway landed for non‑tech readers: even “encrypted” calls can be undone if the network screws up, and the fix lives with the carriers—not your phone.
Key Points
- •ReVoLTE is an attack that exploits keystream reuse in VoLTE due to LTE base station (eNodeB) implementation flaws.
- •Testing of 15 base stations (mainly in Germany) found 12 vulnerable to keystream reuse across consecutive calls.
- •The attack records a victim’s encrypted call, then initiates a second call to the victim to capture known plaintext and recover the reused keystream via XOR.
- •Decryption of the first call is possible for as long as the second call lasts, enabling recovery of prior conversation content.
- •The researchers disclosed the issue via GSMA, demonstrated feasibility in a commercial network, released an app for detection, and presented the work at USENIX Security 2020.