The Essentiagroup, which specialises in health and lifestyle advice, employs 450 people across its Glasgow, Brora and Newcastle offices.
Its advice lines cover issues such as smoking cessation, substance misuse and sexual health. Current clients range from the British Medical Association and NCVO, to the Scottish Government, the COI and the Department of Health.
From offices in Richmond, Tonbridge and Portsmouth, The Listening Company currently manages more than 25 million conversations each year for clients operating in sectors including transport and leisure, automotive, financial services, broadband, telecoms and media, using its own EPI software that combines email, phone and internet channels.
The Listening Company has also recently announced winning new business from car brands Lexus and Toyota.
Neville Upton, chief executive of The Listening Company, said: "This is the next step in our plan to deliver the next generation of contact centres for clients and their customers. The vision of The Essentiagroup echoes the way we see the industry developing."
Joe Costello, managing director of Essentiagroup, said: "I'm convinced that the combined offering of The Listening Company and The Essentiagroup will be perfectly positioned to answer the customer service challenges of today and tomorrow."