So, what a nightmare.
In the deprecated "Get Signal Strength" message:
* Signal strength given as signed integer in 1 dBm units.
* RSSI given as an unsigned integer in (-1) dBm units.
While in the new "Get Signal Info" message:
* RSSI given as a signed integer in 1 dBm units.
Then, these seem to be represented in the same way in both messages:
* ECIO given as an unsigned integer in (-0.5) dBm units.
* IO given as a signed integer in 1 dBm units.
* RSRQ given as a signed integer in 1 dBm units.
* LTE SNR given as a signed integer in (0.1 dB) units.
* LTE RSRP given as a signed integer in 1 dBm units.
Aleksander Morgado