  We study the interior of a Reissner-Nordstr\"om Black-Hole (RNBH) using
Relativistic Quantum Geometry, which was introduced in some previous works. We
found discrete energy levels for a scalar field from a polynomial condition for
the Heun Confluent functions expanded around the effective causal radius $r_*$.
From the solutions it is obtained that the uncertainty principle is valid for
each energy level of space-time, in the form: $E_n\, r_{*,n}=\hbar/2$, and the
charged mass is discretized and distributed in a finite number of states. The
classical RNBH entropy is recovered as the limit case where the number of
states is very large, and the RNBH quantum temperature depends on the number of
states in the interior of the RNBH. This temperature, depending of the number
of states of the RNBH, is related with the Bekeinstein-Hawking (BH)
temperature: $T_{BH} \leq T_{N} < 2\,T_{BH}$.
