Comprehensive 3D optical–electrical–thermal-gain self-consistent simulation of physical processes taking place inside a laser volume of the GaAs-based GaInNAsSb/GaNAs quantum-well (QW) vertical-cavity surface-emitting diode laser (VCSEL) is carried out to examine a possibility to reach the long-wavelength room-temperature (RT) continuous-wave (CW) laser operation in highly detuned devices. The RT CW 1.422-μm lasing emission has been found to be reached practically without troubles. However, to reach the 1.5-μm laser wavelength, it is necessary to increase the QW active region temperature by about 100K, which may be done by a proper increase in the RT CW operation current.