UK firm Spinvox, which converts voicemails into texts, has been bought by speech recognition company Nuance for $102.5m (£64m).
The deal is worth $66m in cash and $36.5m in stock, about a third of the previously rumoured $146m price tag.
Spinvox investor Invesco Perpetual had confirmed in September that Spinvox was up for sale.
In recent months doubts had been cast on how effective Spinvox's speech-to-text software actually was.
The company claims to use advanced voice recognition software for its service, but the BBC found that human operators were also involved in transcribing many messages.