Verizon Wireless will close its acquisition of Alltel this Friday, Verizon said in an SEC 8-K filing late last week.

The merger makes Verizon the largest U.S. wireless carrier, passing AT&T by a few million subscribers. Verizon and AT&T are pulling away from Sprint Nextel, which continues to lose subscribers in recent quarters.

Verizon announced its plan to buy Alltel in June, followed by approval from the Department of Justice in October, the FCC in November and the FTC in December.  Officials aimed for closure by the end of 2008 but missed that target.

Alltel attempted to buy Sprint, but wasn’t able to fund the deal because of last year’s credit crisis, the Arkansas News said.

With regulatory details behind them, Verizon/Alltel can move forward with integrating networks, eliminating redundancies, merging customer service units and developing new service plans.

Other challenges for Verizon in 2009 include ongoing development for its LTE plan, finding ways to increase data revenue without radically altering its text fee structure and expanding its services to allow third-party network devices.

Separately, Verizon today said its customers sent 1.6 billion text messages on New Year’s Eve last week and 1.7 billion on Christmas.