Why 5G drops to 4G when you walk indoors.
By SignalFix · Facts checked 2026-10-02
Which 5G you're on
Indian operators run 5G mainly on band n78 (3.3–3.67 GHz). Jio also uses n28 (700 MHz), a low band that travels further and gets through walls better. Both Jio and Airtel hold n258 (26 GHz) millimetre-wave spectrum, which barely gets indoors at all.
Higher frequency, more loss
In the 3GPP model used to design 5G, concrete loss rises by about 4 dB for every GHz. Concrete costs around 19 dB at 3.5 GHz against about 8 dB at 700 MHz. Through two concrete walls, that difference compounds.
Why your phone falls back to 4G
Your phone picks the best usable connection. When 5G becomes too weak, it drops to 4G, which is often on lower frequencies that reach the room better. The 5G icon disappearing indoors usually means your phone is doing its job.
If calls drop or data stalls on 4G too, the problem isn't 5G. It's the walls, for every band. Why signal is weak indoors.
What actually helps
- Measure before you spend: read your signal in dBm, per room.
- For calls, Wi-Fi calling sidesteps the walls entirely where your Wi-Fi is strong.
- For whole flats or offices, a SignalCheck shows what reaches each room on each network and band, and what will fix it lawfully.