The nation's lobby for wireless carriers is warning consumers to expect delays while attempting to use the mobile phone on Inauguration Day when Barack Obama is sworn in as president.

CTIA-The Wireless Association expects between 2 million and 4 million visitors to attend Washington, DC, on Jan. 20 to witness the swearing-in and attend festivities associated with the 44th president's arrival.

"You're potentially talking about the market expanding by 4 million people," said Joe Farren, assistant vice president of public affairs at the CTIA, Washington, DC. "This would be the mother of all demand peaks.

"On a day like Inauguration Day, if projections are accurate, data usage by 4 million people could pose problems to the wireless network in DC," he said.

Carriers expect a crowd of 1 million on the National Mall across from the Capitol where the Inaugural ceremony will take place.

Washington has a resident population of about 588,000, swelling to 1 million during the workweek due to commuters from neighboring towns and cities.

The Washington metropolitan area has 5.8 million people, covering the District of Columbia as well as the suburbs and exurbs in the Beltway.

Carriers are taking several steps to meet this anticipated spike in demand for President-elect Obama's inauguration.

Among the many initiatives are adding new radio channels to support existing cell sites and putting in place portable sites such as Cells on Wheels and Cells on Light Trucks.

Another measure to add network capacity is more backhaul capacity and connections with the Public Switched Telephone Network to ensure maximum capacity for mobile subscribers within the physical limits of spectrum and sites available to carriers.

For example, Sprint Nextel plans to boost its network capacity by 40 percent for wireless service and 90 percent for its walkie-talkie-like service.

AT&T, Verizon Wireless and T-Mobile will also add capacity to their networks.

That said, CTIA members aren't taking any chances. The association has come up with a list of recommendations for Washington residents and visitors.

For example, the CTIA advises that mobile consumers text instead of talk. Text messages and emails transmit easier when wireless networks are too congested to make voice calls.

Next, consumers should take photos and save, and then text them later. The rationale? Sending mobile photos and videos take up a huge amount of bandwidth on mobile networks.

The association is recommending that consumers wait until the Inaugural events are over to send the images and video to friends and family.

Finally, visitors and residents should have a backup plan. They should establish a pre-determined place and time t meet with each other or move to an area where there is less congestion. This way there are fewer back-and-forth "Where are you?" calls.

"If we do indeed have the 4 million projection realized, then regardless of everything that carriers are doing to increase capacity, there still may be calling and text messaging delays," Mr. Farren said.