Avaya (AV) says it is in a deal to acquire closely held Traverse Networks.

The Basking Ridge, N.J., office phone networking shop says it has bought the Fremont, Calif., mobile email specialist to add to its so-called unified messaging service.

Traverse makes phone systems that allow users to manage where and how they receive calls and voice mails.

Avaya is one of the leaders in office phone equipment, but in recent years

Cisco's

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Internet protocol phone products have been taking larger bites of the business communications market.

The Traverse acquisition is expected to help Avaya boost its strength in wireless by adding more features for cell phone users. Avaya's messaging chief Eileen Rudden says the company has "partnered with industry leaders including

Nokia

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and

RIM

( RIMM) Blackberry to extend mobile enterprise communications to these familiar personal productivity devices."

Avaya shares dropped 19 cents in early trading Thursday to $13.19.