Despite a slowdown in its second-quarter subscriber growth, Clearwire CEO Bill Morrow expects business to pick up in the fourth quarter.

“Given our planned launch schedule and assuming similar initial consumer responses in new-built markets, we anticipate fourth-quarter net subscriber additions will be substantially higher than all other 2009 quarters combined,” Morrow said in a conference call with analysts.

His rosy prediction came amid a slump in the company’s second-quarter net additions, which fell to 12,000 compared with 18,000 last year. The company did not provide any guidance for next quarter.

Aside from net adds, the company also posted worsening churn and a slump in ARPU. Churn hit 2.8 percent over last year’s rate of 2.6 percent. Though ARPU improved over last year, it fell on a sequential basis, hitting $39.47 in the second quarter compared with $39.52 in the first quarter.

Morrow assuaged concerns over the figures, saying the rise was related to the start of the school year and the company’s decision to dedicate fewer financial resources to existing pre-WiMAX markets in anticipation of mobile WiMAX upgrades.

As for ARPU, the company said that promotional pricing played a role in offsetting an increase in sales of higher-priced mobile service plans, and there was an uptick in bundled sales of its new services, such as VoIP and PC cards.

Clearwire is in the midst of a massive build-out of its mobile WiMAX network, which now covers 23.1 million people in multiple markets including Las Vegas and Portland, Ore.

So far this year, the company has spent $646 million on its network. The company plans to spend between $1.5 billion to $1.9 billion this year and says it is on track to reach its previously stated goal to cover 120 million people in 80 markets by 2010.

Clearwire is backed by an impressive roster of investors, including Sprint, Comcast, Google and Time Warner Cable. Clearwire has begun reselling its WiMAX service to some of its investors, a move that is a major part of its business strategy.

Clearwire’s primary investor, Sprint, announced today that it would launch 4G service in 17 new markets this year alone. The new markets are concentrated in Texas, with deployments also planned in Charlotte, N.C.; Boise, Idaho; and Bellingham, Wash.

The additional markets join the previously announced markets of Atlanta, Chicago, Dallas-Fort Worth, Honolulu, Las Vegas, Portland, Philadelphia and Seattle.

At the end of June, Comcast began selling Clearwire’s service in Portland under the “High-Speed 2go” brand. The service was followed by a launch in Atlanta at the end of July. By the end of the year, Comcast will offer the service in several more markets, including Chicago and Philadelphia.

Time Warner Cable announced plans in late July to launch a high-speed wireless broadband service on the Clearwire network in four cities, including Charlotte and Dallas.

During the call, Clearwire also addressed concerns over the progress of its 4G device ecosystem. The company said that manufacturer pricing of its USB dongles was 40 percent less than last year as the WiMAX ecosystem continues to scale.

It also cited WiMAX compatibility in several Dell and Samsung products, including the Samsung Amandi, which it described as “a mobile WiMAX-enabled handheld device that combines the abilities of a PC with the size and portability of a mobile phone.”

Lastly, the company said Mac compatibility for its dual-mode modems was expected to be rolled out in the fourth quarter of this year.

More Broadband Direct 08/12/09:
•  Clearwire gives rosy outlook despite slowdown
•  Post FCC waiver, Evolution scores customer win
•  RGB Networks adds MPEG-4 to bandwidth manager
•  Rovi, TNS Media team up on TV, STB measurement
•  Verizon adds remote DVR, multimedia features for FiOS subs
•  Survey: Companies reprioritizing IT needs
•  Signs of life in North American broadband market
•  Verizon "pre-churners" snub Palm, look to iPhone
•  Microsoft, Nokia team up for enterprise endeavor
•  Broadband Briefs for 08/12/09