As Tropical Storm Isaac approaches the Gulf Coast, carriers have made an effort over the past couple days to ensure customers of their readiness in case of disaster. Isaac is expected to become a hurricane sometime in the next 48 hours, with an eerie trajectory path that puts it on course to possibly make landfall in New Orleans on the anniversary of Hurricane Katrina's devastating arrival on Aug. 30, 2005.

Communications are often the first things to go and also what's needed most, as emergency crews and resident work to coordinate relief and rescue efforts.

AT&T says that it has invested more than $600 million in its Network Disaster Recovery (NDR) initiatives. Formed in 1991, the NDR arsenal of equipment includes more than 320 technology and equipment trailers that can be quickly deployed to respond to events, such as hurricanes. AT&T says it regularly conducts readiness drills and simulations throughout the year to ensure its networks are prepared for any kind of disaster.

At present, it looks like Isaac will just graze Florida, but should it do more damage there, Sprint says it will be ready.

Ahead of the 2012 hurricane season, Sprint invested close to $140 million to increase capacity and expand its wireless networks in the state of Florida, including more than $45 million in the Miami-West Palm Beach region; approximately $2.7 million in the Florida Panhandle; more than $18 million in Tampa; $5.1 million in the state’s Gulf Coast region; and close to $40 million in Orlando. Since January 2011, Sprint has added more than 80 new cell sites throughout the state.

Sprint has made a number of specific preparations, such as: "hardening" 70 percent of its cell sites in Florida with permanent generators in case of a loss of local power; ensuring all Sprint network reservist strike teams are on standby and ready to deploy following Isaac’s landfall; and monitoring all Sprint cell sites that support the contraflow and evacuation routes as designated by the Florida Department of Transportation.

C Spire Wireless, which serves a customer base largely located in the south, said in a press release that it expects Issac will develop into a full-fledged hurricane over the next several days and cause extensive damage along the Mississippi Gulf Coast.

"We are taking this situation very seriously and we’ll be ready for whatever occurs. Our preparations are designed to give customers maximum reliability from their wireless phones at the time of greatest need," said Eric Hollingsworth, vice president of network operations for C Spire Wireless, in a statement.

Hollingsworth said the company has put restoration teams on stand by and is massing equipment and materials to protect critical company facilities and cell sites. The company uses back up batteries, as well as diesel generators at sites and has made arrangements for replacement fuel supplies in case normal fuel delivery options are interrupted by commercial power outages.

C Spire also relies on an extensive network of microwave technology that can circumvent damaged or destroyed landline systems and ensure that wireless calls can be routed to their final destination, Hollingsworth said. “This microwave technology is critical to support communications during natural disasters when landline systems are inoperable,” he added.

In a recent blog post, Debi Lewis, a spokeswoman for Verizon Wireless, reminded customers that their devices will now alert them to severe weather threats or national emergencies via Wireless Emergency Alerts (WEAs).

WEAs became available on certain phones starting in April. Formally known as the Commercial Mobile Alerting System (CMAS), the system allows authorized government agencies, such as the National Weather Service, to initiate a process to send messages to wireless phone users in a targeted geographic area. Carriers transmit the alerts to cell towers within the target geographic area, where they are received by WEA-capable devices that are operating in the area.

Lewis explains that WEAs are free messages that will not be sent to anyone roaming outside the target geographic area. Only WEA-capable devices can receive the alerts. Verizon Wireless currently offers 13 such devices, which are marked with a special logo both in stores and online. Users with SMS or text blocks on their accounts will still receive these alerts because they are delivered differently than regular texts.

The carriers, in cooperation with government agencies, such as the Department of Homeland Security, have put an increasing emphasis on disaster preparation over the past few years. A government report following in the wake of Hurricane Katrina,  found that “basic operability” of wireless and wireline networks was nearly non-existent after that storm made landfall.