BellSouth will spend between $400 million and $600 million to restore the network damage done by Hurricane Katrina, the company estimated today. That includes both expenses and capital costs, but is just a preliminary estimate, according to the company.

That word came as the telecom and tech industries are rallying on behalf of the areas hit hardest by Katrina and exploring ways to use technology, such as unlicensed wireless spectrum, in ways that aid the relief effort. The Federal Communications Commission is working with wireless ISPs, who are coordinating a national effort to get voice over IP and other communications up and running in New Orleans and other areas where restoring traditional communications will take longer.

The FCC stayed open through the weekend to coordinate emergency relief efforts and issue a series of orders removing restrictions on number portability and rules intended to prevent ‘slamming’ in order to allow customers to switch their service quickly to whatever might be available.

As of Monday, BellSouth believes 810,000 lines are still out of service and 19 of its 131 Central Offices were still awaiting restoration. Those damaged COs serve about 187,000 access lines, and 166,000 of those lines are in the New Orleans area.

“Restoration begins with our central offices and high-capacity trunk lines and the vast majority have been repaired,” said BellSouth CTO Bill Smith, the company’s spokesperson for the restoration effort. “We are making steady progress as we gain access. Most customers will be restored within 30 days. However, some communities may take longer to rebuild in certain cases depending on when residents and businesses are able to return to these most affected areas and the time it takes to rebuild needed local infrastructure. New Orleans is an atypical situation given the floodwaters and access issues, and because of this, we will track restoration activity in New Orleans separately.”

The effort to get wireless networks up and running was paying off. T:Mobile said Saturday that most of its network serving downtown New Orleans was operational, although like other wireless networks, was sometimes unable to handle the call volume.

Cingular officials said Monday that it had completely restored service in Mobile, Ala., and Jackson, Miss., and had restored most of its coverage in Biloxi, Miss.The company said it had some coverage in New Orleans, using satellite and microwave connections to replace T-1 lines in connecting base stations, and continues to make that region a priority. Cingular also reported some coverage in Meridian, Hattiesburg, and Gulfport, Miss.

Telecom companies are responding in traditional ways – sending crews to the affected areas from across the country and donating money to relief efforts – and nontraditional ways. Verizon set up a special 411 Directory Assistance service that automatically routes callers who say “Katrina relief” to a set of operators equipped with a constantly growing list of phone numbers for shelters and other relief facilities. Cingular used a text-messaging campaign to its subscribers to encourage them to make donations to the relief effort.

The WISP community also rallied, inspired by the FCC’s Friday afternoon decision to lift restrictions on non-commercial traffic using the educational spectrum. Part-15.org, a Web-based organization of spectrum-exempt WISPs is soliciting help and coordinating volunteer groups from around the country.