LONGMONT - The parent company of Intrado Inc., one of the larger private employers in Longmont, has filed for an initial public share offering worth as much as $532 million.

West Corp., a company based in Omaha, Nebraska, which bought Intrado for $465 million in 2006, said Monday it plans to sell 21.275 million shares of common stock to investors at from $22 to $25 a share. It wants to be listed on the Nasdaq exchange as "WSTC" and said in its filing that it intends to use proceeds from the stock offering to repay $450 million in senior notes that are due in 2016.

The filing, made through a prospectus, awaits U.S. Securities and Exchange Commission approval.

Intrado, which has about 800 employees at its facility at 1601 Dry Creek Drive in Longmont and 1,200 companywide, provides emergency communications infrastructure, systems and services to governments and most U.S. landline, wireless and VoIP carriers as well as government agencies. Intrado provides the software that routes 911 calls to the correct agency. A 2004 Boulder County Business Report IQ Award winner, Intrado also has facilities in: Lisle, Illinois; Austin, Texas; and Montreal.

West generates $2.6 billion in sales a year from cloud computing and handling other companies' customer service calls. Its InterCall division handled 134 million conference calls in 2012, according to company publicity.

Goldman, Sachs & Co. and Morgan Stanley & Co. LLC are acting as lead bookrunners for the offering, arranging the deal and selling the shares to investors. Merrill Lynch, Barclays, Citigroup, Deutsche Bank Securities and Wells Fargo Securities are acting as joint bookrunners; Baird and William Blair are acting as co-lead managers; and Evercore Partners and Sanford C. Bernstein are acting as co-managers. The investment banks will have an option to buy almost 3.2 million more shares of West Corp. if demand warrants it.

Intrado was founded in 1979 as a consulting business called Systems Concepts of Colorado Inc. In 1979, Intrado launched an initial public offering of common stock and was publicly traded on Nasdaq under the ticker symbol TRDO. It acquired Lucent Public Safety Systems in 2001. After buying Intrado in April 2006, West bought HBF Group Inc. and Positron Public Safety Systems, making them part of Intrado. It also bought another Colorado company - Louisville-based conferencing company Raindance Communications - for $113 million.

West employs 3,700 people in the Omaha area and a total of 35,700 globally. The overall company reported a profit of $126 million in 2012, more than double its 2010 figure according to SEC filings.

West was publicly traded once before, proposing to sell 5.7 million shares in 1996 and ultimately realizing net proceeds of $107.7 million. It was taken private by Thomas H. Lee Partners LP and Quadrangle Group LLC for about $4 billion in 2006. A planned IPO announced by West in 2009 never came to fruition.