T-Mobile, in the midst of its takeover by AT&T, has selected Big Fuel to serve as its first social-media agency of record.

The telecom giant, which is awaiting completion of a $39 billion deal to be acquired by AT&T, invited a number of digital shops including Big Fuel, AKQA, SapientNitro and Dachis Group to vie for the seven-figure budget account, executives familiar with the pitch said.

The company suggested that the move to hire a social-media agency comes as it has seen more engagement with consumers ahead of the finalization of a $39 billion deal to be acquired by AT&T. "Over the past six months, we have grown our fan and follower base on Facebook and Twitter exponentially," Reid Walker, VP-corporate communications at T-Mobile USA, said in a statement.

Big Fuel will lead social strategy and analytics, integration of social into existing marketing efforts, brand channel oversight, content development and social media network activation.

The win comes six months after longtime advertising executive Jon Bond took the helm at Big Fuel. Mr. Bond became CEO in January and has since grown the agency from 80 to 170 people, as well as announced plans to open a Seattle office as a majority Big Fuel clients, including Microsoft, are located on the West Coast, he said. This T-Mobile win, he told Ad Age , will enable the firm to hire 20 to 25 more people.

"What we're really focused on is the social AOR for a complex client so this is right in our sweet spot," Mr. Bond said. He associated complex with "a lot of moving parts," including products, technology and agency collaboration. The overall idea for T-Mobile, he said, is to "martial social-media assets to create scale."

Big Fuel joins an agency roster at T-Mobile that currently includes Publicis for creative and Waggener Edstrom for PR.