Leading global communications company Nortel Networks Corp. will announce an acquisition today to bolster a new services division that deals with the sale and rental of software via the Internet, a source close to the deal said. The source would not indicate which company was being bought. Brampton, Canada-based Nortel launched a new division in December to push the so-called application services provider, or ASP, market, estimated to be worth $23 billion by 2003, according to research firm Dataquest. Working with Hewlett-Packard Co. and three software firms, Nortel said in December that it would help companies that provide services over the Internet to certify, deliver and support applications with services that it would launch in the first quarter. Nortel shares rose $3.06 to close at $121 on the NYSE.