Blyk was launched in the UK just seven months ago and is aimed at 16-24 year-olds. It gives its users free texts and phone minutes every month equating to around £280 a year in savings. In return, customers must receive up to six advertising messages per day.
Shaun Gregory, Blyk's UK chief executive, said: "Young people have embraced Blyk because it makes phone bills and contracts a thing of the past. We believe that communication should be free like most other forms of media in the UK."
The company claims that its "highly-targeted" advertising has achieved an average response rate of 29%. Advertisers who have signed up to Blyk include brands Xbox, Adidas, Penguin, Brylcreem, and the RSPCA.
Gregory said: "Reaching 100,000 members is significant for advertisers because it gives them the opportunity to engage with a mass youth audience in a highly efficient and cost-effective way."
He added that the UK's 7m-plus 16- to 24-year-old phone users gives Blyk a "huge potential for growth".
Blyk was founded by former Nokia president Pekka Ala-Pietila and is funded by investment bank Goldman Sachs.