https://cmlmicro.com/products/analogue-digital-voice/product/cmx618-638-ralcwi-vocoder-ic-s/
CMX618/638 – RALCWI Vocoder IC’s - CML Micro
The CMX618 and CMX638 are low-cost RALCWI vocoder ICs delivering near toll-quality digital voice at 2400bps, suited to PMR, DMR and secure voice systems.
ralcwivocodercmlmicro