In 5G NSA, the phone stays attached to a 4G cell and uses 5G only as extra throughput. In 5G SA, 5G carries everything, including voice. The icon shows “5G” in both cases: only a measurement says which one.
The 5G icon is not a measurement
The icon depends on a carrier and device setting. On most networks it appears as soon as a 5G cell is declared available in the area, even before the phone uses it. It says “5G is around here”, not “you are on 5G”.
In the field, a phone showing 5G may be making a call on 4G, transferring data on 4G, or attached to a 5G cell that vanishes ten metres further on.
NSA: 5G anchored on 4G
In NSA (Non-Standalone, EN-DC) mode, the device is first connected to an LTE cell, the anchor. The NR cell is added as a secondary carrier for throughput. Signalling, voice and mobility stay on 4G.
Consequence: the quality of an NSA link depends first on the 4G anchor cell. Superb 5G NSA on mediocre 4G gives high throughput and mediocre calls.
SA: a 5G core
In SA (Standalone) mode, the device is connected to an NR cell linked to a 5G core network. Voice goes over VoNR, latency drops, and 5G-specific features (network slices, guaranteed low latency) become possible.
SA is rolled out progressively, band by band and carrier by carrier. One site may have SA for one carrier and NSA for another, on the same frequency.
What it changes for a router or a connected device
A 4G/5G router placed on 5G NSA lives at the pace of its 4G anchor cell: that is the cell to measure and track. An IoT module most often uses neither: it stays on LTE, LTE-M or NB-IoT, and the presence of 5G on the site does not concern it.
Choosing a location for 5G therefore means first choosing a good 4G cell in NSA, or verifying that an SA cell is really stable, pass after pass.
How Scout distinguishes LTE, NR, NSA and SA
Scout displays the technology actually detected for each cell: LTE or NR, with its band. With the 5G module, the 4G/5G scan documents the NR cells present, their band (n78, n28…), their level and the number of passes in which they are seen.
The NSA/SA distinction is read from behaviour: an NR cell that exists only alongside an LTE cell of the same carrier, and is absent from the list of cells a device can camp on, is an NSA carrier. An NR cell a device can register on alone is SA. Scout reports what it detects and does not assert what it does not.
A NoMYST example
