Sonitrol, headquartered in Berwyn, Pa., provides security monitoring services, access control and fire detection systems to commercial customers in North America via two monitoring centers and a national multi-channel distribution network. Ranked No. 8 on the SDM 100, Sonitrol brings a strong brand, capabilities in audio-verified monitoring and a substantial national account base to Stanley’s Convergent Security Solutions platform. Sonitrol, with revenue totaling approximately $110 million will report into Stanley’s Convergent Security Solutions business, which had 2007 revenues approaching $600 million.

Stanley also purchased the retail branch business of National Guardian Security Services Inc., Norwalk, Conn. The purchase includes both commercial and residential accounts across the United States with strong concentration in California, Missouri and Kansas. Terms of the sale were not disclosed.