In human cells IL-23 binding leads to phosphorylation and activation of TYK2 and JAK2 (Parham et al 2002).
Inferred from mouse:
The intracellular domain of Interleukin 12 receptor beta 1 subunit (Il12rb1), spanning amino acid residues 592–656, is crucial for Interleukin 23 complex–induced cellular proliferation and Signal transducer and activator of transcription 3 (Stat3) phosphorylation (Floss et al. 2016).
As it is not clear what induces JAK2 and TYK2 kinase phosphorylation this is represented here as a black box event.