The Motorola MT-500 "Handy Talky" is a police-frequency radio used by the Ghostbusters in the first film. The correct model is the MT-500 3-6 channel UHF, with no scan knobs, PL boards, or dial pads on the face. The antennas are the 2.0" x 0.5" models. They are carried in the standard issue MT-500 holsters (without the straps).
The radios used in the 2009 video game are noticeably thinner than the MT-500, possibly based on the MT-2100 model. They also sport 7.0" x 0.5" antennas and are conveniently clipped to the left strap of the Proton Pack.
MT-500 without the Antenna, Photo by Keith Marshall
MT-500 Holster
Venkman's MT-500 with the 2.0" x 0.5" Antenna
Stantz's Radio in the 2009 Video Game - Note the fictional brand.
The radios used in 2009 video game greatly resemble the Motorola MT-2100.