Quick Answer
If the outdoor signal is usable but the indoor signal is not, the building is shielding the signal. If the outdoor signal is already weak, the problem is the network. If no usable signal exists anywhere outside, a booster cannot create one.
The three causes behind “no signal”
A phone showing one or two bars does not tell you whether the problem is outside the building or inside it. Measure the outdoor signal first, then compare it with the indoor level. The difference separates the three cases below.
| Cause | Outdoor check | What usually works |
|---|---|---|
| A. Building shielding | -85 dBm or better outside; much weaker inside | Booster with indoor antennas; zone the coverage by floor or area |
| B. Weak outdoor coverage | -95 to -110 dBm outside; no stable usable signal | High-gain directional donor antenna, mast height, low-loss feeder and a higher-power host |
| C. No coverage | No usable signal on the roof or high point, on any operator | A booster is not the answer; use VoWiFi, satellite backhaul, private LTE or an operator-led site |
How to tell in about ten minutes
Use a phone in field-test mode or a measurement app. Walk around the outside of the building, then test the worst indoor rooms and the proposed equipment location.
- Record outdoor RSRP on at least two sides of the building and on the roof if accessible.
- Record indoor RSRP in the worst room, the middle of the floor and the basement or stairwell.
- Note the wall, roof and window materials between the outdoor point and the indoor point.
- Repeat on each operator you need to cover; one operator may be usable while another is not.
What each result means
A building-shielding case is the most common booster project: the outdoor signal is usable, so the job is to capture it cleanly and distribute it indoors without self-oscillation. A weak-coverage case needs more attention at the donor end than at the amplifier. A no-coverage case should be told honestly and redirected to an alternative path.
If the outdoor reading is between -95 and -105 dBm, do not assume a larger amplifier will solve it. First check whether a higher-gain antenna, a better mounting height or a shorter feeder run can raise the donor level.
These thresholds are practical starting points, not a substitute for a site survey. Building materials, frequency and operator load all change the result.
Book a remote diagnosis
Share the site conditions and we will reply with a preliminary assessment and the measurements still needed.
Frequently Asked Questions
Can a booster fix a building with no outdoor signal?
No. A booster amplifies an existing signal; it does not create coverage. If no usable signal can be measured at the roof or a high point, the site needs VoWiFi, satellite backhaul, private LTE or an operator-led solution.
Why does only one room or floor have no signal?
Local concrete cores, metal plant rooms, Low-E glass, basements and long corridors can create a local shadow while the rest of the floor still has usable signal. This is usually a distribution problem, not a total lack of outdoor coverage.
What should I send first?
Send the outdoor RSRP at the proposed donor position, the indoor RSRP in the worst area, the operator and band if known, and a floor plan or photos. That is enough for a first remote assessment.