"A tweet's only 140 characters," Twitter's chief revenue officer, Adam Bain, said last month. "When consumers want to learn more, spend more time, or get deeper in terms of engagement, we think they'll end up on the brand page."

According to an email from a Twitter account executive obtained by Ad Age , the roll-out of brand pages to a larger group of brands and partners will begin Feb. 1, and advertisers must have an active insertion order in Twitter's system of $25,000 to qualify.

The company's launch group of 21 marketers was made up of its higher-spending media partners who had committed a minimum of $2 million to ad spending on the platform, according to an industry source who was informed by two Twitter sales representatives. A source at one of the launch brands confirmed that their company had made a yearlong spending commitment on Twitter ad products of at least $2 million.

The company also announced last month that it was partnering with some charities and individuals for the launch of brand pages. One of them is the American Red Cross.

Twitter had no comment on either the release date of new brand pages or ad spending minimums required of brands to qualify for one.

Twitter's global ad revenue was projected to reach $139.5 million last year and approach $400 million in 2013, according to eMarketer. It launched its advertising program in April 2010 with six brands signed up to use promoted tweets.