In case you're interested (I know you're not) cellphones ALEWAYS use maximum power when establishing a call, data or otherwise, and rapidly ramp down to the minimum power required to maintain reliable communications. Here's a more detailed description of how it does that. I'm willing to bet real money that the tests were only done at maximum power for the article.s that are referred to in your link. Anyway; Here follows the description of REAL WORLD cellular handset communications. Spoiler: you really want to be as close to the base station as is possible to reduce the power your handset (MS) trqansmits with.
For UMTS/WCDMA (3G), the inner loop (fast closed-loop) power control allows the UE (cellphone) to adjust its uplink transmit power in steps (typically 1 dB) at 1500 Hz (once per slot) based on TPC commands from the base station. This keeps the received SIR close to the target, minimizing interference and battery use while maintaining link quality.
umtsworld.com
The lowest/minimum controlled transmit power for the UE in UMTS is typically -44 dBm (or sometimes specified down to around -50 dBm in early discussions/requirements). This is the floor when both inner/closed-loop and open-loop power control indicate minimum power.
etsi.org +1
In watts: -44 dBm ≈ 4 × 10^{-8} W (0.00000004 W or 40 nanowatts). -50 dBm would be 10 nW.
quora.com
This is a huge dynamic range from the typical max of +21 to +24 dBm (Power Class 4 or similar; ~0.125–0.25 W).
3gpp.org
Transition to inner loop power control: Inner loop starts once the dedicated physical channel (e.g., DPCH) is established after call setup/RRC connection. Open-loop provides the initial power, then closed-loop (inner) takes over rapidly for fine adjustments. The UE applies TPC steps in the slot immediately after deriving the command. Full power ramp-down to minimum can occur over multiple slots (e.g., at 1 dB/step, dropping tens of dB takes milliseconds to tens of ms depending on the required reduction and algorithm). Exact call-setup timing to stable inner-loop operation depends on network configuration but is generally quick (within the first few slots/frames after DCH allocation).
umtsworld.com
LTE (4G) is similar but uses a different mechanism: Minimum output power is -40 dBm (with max typically 23 dBm for Power Class 3, giving ~63 dB dynamic range). Closed-loop adjustments use TPC commands in DCI.
ntia.gov
5G NR has analogous uplink power control (open-loop + closed-loop with TPC commands) to ensure minimum power is used. It follows a formula like:P_TX = min(P_CMAX, P0 + α × PL + Δ_TF + f(i)) (simplified for PUSCH, etc.),where closed-loop adjustments (via TPC in DCI) provide fast corrections slot-by-slot. Minimum output power is low (e.g., around -13 dBm or better in some FR2 specs, but effectively very low in practice for FR1, similar to LTE). Typical handheld UEs use Power Class 3 with max 23 dBm. This supports efficient link budgets by using only the power needed.
techlteworld.com +2
In all cases (3G/4G/5G), power control dramatically reduces average transmit power (often to low single-digit dBm or lower when the UE is close to the base station/good conditions), saving battery and reducing interference. Actual minimums can depend on band, UE power class, and exact 3GPP release, but the systems are designed for wide dynamic range down to very low levels. Real-world values also consider tolerances, off power (-50 dBm range), and implementation.
(description from Grok, but it is really how a handset works)