4G is the fourth generation of mobile networks, based mainly on LTE, delivering all-IP mobile broadband with speeds from tens to hundreds of Mbit/s.
How 4G works
Unlike 3G, 4G is an all-IP network: even voice calls are carried as data (VoLTE). The dominant technology is LTE (Long Term Evolution), first launched commercially in Stockholm and Oslo in December 2009, and its upgrade LTE-Advanced, which combines several frequency bands (carrier aggregation). Low latency and high throughput made 4G the base for mobile video, app stores and today’s IoT variants LTE-M and NB-IoT.
Why 4G matters for security
LTE authenticates the network as well as the phone and encrypts radio traffic, but researchers have found several weak spots:
- Downgrade attacks – IMSI catchers can push phones to 2G or 3G, where interception is easier.
- No integrity protection for user data – the 2018 aLTEr attack showed that encrypted traffic can be modified in transit, for example to redirect DNS requests.
- Signalling abuse – the Diameter protocol between operators can be misused for location tracking, similar to SS7 in older networks.
5G standalone networks fix some of these issues (for example by encrypting the subscriber identity), but 4G will remain the fallback layer for years.
What to keep in mind
- Use end-to-end encrypted messengers and HTTPS; do not rely on radio encryption alone.
- Where available, disable 2G on your phone to limit downgrade attacks.
- Prefer app-based or hardware MFA to SMS codes.
