* Nextel Communications' plan to exchange billions of dollars and some of its existing airwaves for new cellular spectrum from the Federal Communications Commission is legal, the Government Accountability Office found yesterday. In a letter to Sen. Frank R. Lautenberg (D-N.J.), the agency said the plan, which has not been finalized, does not violate laws that prohibit federal agencies from selling public resources. Nextel said the airwaves swap will help clear up interference with police and fire radios.

Separately, the Reston wireless company said in its quarterly filing with the Securities and Exchange Commission that expensing its employee stock options during the third quarter would have reduced its earnings by $39 million. On Oct. 22, Nextel reported $586 million (52 cents a share) in profit. If stock options had been counted as an expense, as proposed by critics of regulations that permit off-the-books treatment of options, the company would have reported a profit of $547 million (48 cents).

* Metrocall Holdings of Alexandria, which sells paging services, said its shareholders yesterday approved its merger with Arch Wireless to create USA Mobility. The merger also has been approved by the Justice Department, but the Federal Communications Commission has yet to act on the deal, which would combine the two biggest paging companies. Also, a group of Metrocall shareholders won the right to have their shares appraised in an attempt to claim more compensation. The appraisal request violates the conditions necessary to close the merger, so the boards of directors of the merging companies would have to vote to waive that condition.

* LCC International of McLean, which designs and maintains wireless networks, said its profit for the third quarter ended Sept. 30 was $1.2 million (5 cents a share), on revenue of $56.3 million. During the same period last year, the company lost $1 million (5 cents) on revenue of $29.4 million. For the first nine months of the year, LCC earned $981,000 (4 cents) on $154 million in revenue, compared with a loss of $7.2 million (34 cents) on revenue of $64.7 million during the same period a year earlier. The company said sales benefited from an increase in demand from wireless companies. Shares closed at $4.59, up 24 cents.

* Mobile 365, a Chantilly mobile messaging company, said it was awarded a license by the Ministry of Information in China. The license authorizes Mobile 365 to offer mobile services nationally in China. Matthew Talbot, managing director of the Mobile Services Asia unit, said the license enables the company to offer mobile applications that could reach more than 310 million users.

* Science Applications International, a McLean research and engineering firm, has formed Trusted Insight, a group devoted to providing commercial customers with business-focused security consulting services. Trusted Insight will offer information and physical security services, including technical assessments, consulting and risk management.

* WILink, an online investor relations company in London, acquired Communicast, a Herndon managed Web conferencing and webcasting company, for $3.25 million in cash and stock. WILink's North American operations are based in Richmond. Communicast is the first company WILink has acquired in an effort to expand its Vcall webcasting unit and to offer a new range of web conferencing services to the non-investor relations functions of its 3,500 clients. Communicast offers interactive functions including polling, testing and whiteboarding. All current employees of Communicast will join Vcall.

* Guilford Pharmaceuticals of Baltimore lost $14.5 million (33 cents a share) on $17.3 million in revenue during its third quarter, compared with a loss of $13.3 million (46 cents) on $5.4 million in revenue during the corresponding quarter a year ago. Shares fell 17 cents to close at $4.25.

Compiled from reports by Washington Post staff writers.