Assurant is buying Signal from a private equity fund managed by Stone Point Capital LLC and Signal's management.

The transaction is expected to close during the fourth quarter.

Signal, of Wayne, Pa., generates annual revenue of about $330 million by servicing service contracts for about 4.2 million wireless subscribers. The company employs about 700 people in four locations.

Assurant has provided underwriting and marketing support for Signal since 2001. The deal will not add to gross written premiums, the company said, but will add about $150 million revenue to its Assurant Solutions unit, which handles specialty insurance and extended service contracts. The deal is expected to add to earnings beginning in 2010.