It is shown that the hidden conformal symmetry, namely SO(2,2)∼SL(2,R)L×SL(2,R)R symmetry, of the non-extremal dyonic
Reissner-Nordstr\"om black hole can be probed by a charged massless scalar
field at low frequencies. The existence of such hidden conformal symmetry
suggests that the field theory holographically dual to the 4D
Reissner-Nordstr\"om black hole indeed should be a 2D CFT. Although the
associated AdS3 structure does not explicitly appear in the near horizon
geometry, the primary parameters of the dual CFT2 can be exactly obtained
without the necessity of embedding the 4D Reissner-Nordstr\"om black hole into
5D spacetime. The duality is further supported by comparing the absorption
cross sections and real-time correlators obtained from both the CFT and the
gravity sides.Comment: 18 pages, no figure, typos correcte