Vocus experienced 44 per cent global growth last year. Montpellier's account, won following a four-way pitch, will focus on raising the company's profile in the UK.
Account director Lisa Pringle will head the account, reporting to Vocus MD Andrew Muir.
Muir said: ‘Our systems offer clients what is often seen as the Holy Grail in PR measurement. By ensuring that press coverage isn't just seen in isolation to the activity on the account, we can provide insights into what makes a successful campaign.'