The companies are still in a effort to grant full 3G coverage yet, but the nation's major carriers are already looking ahead to deploying 4G, as they continue their 3G rollout.

T-Mobile USA on Tuesday announced that it has successfully upgraded to HSPA 7.2 for its 3G network. Meanwhile, AT&T announced that it had enabled its own 3G network for HSPA 7.2 as well.

The third generation mobile telecommunications technology is based on the Universal Mobile Telecommunications System (UMTS) standard. AT&T and T-Mobile are both using the technology to build upon GSM service and offer a faster service compared to earlier standards like EDGE. UMTS offers faster data transfer rates than EDGE.

Sprint was the first one to begin the 4G race, as they continue their 3G rollout. Also, now T-Mobile has revealed that its 3G upgrade of its current network is complete and it is beginning its own effort to deploy 4G technologies focusing on the Evolved High Speed Packet Access (HSPA+) standard. It has already deployed it in Philadelphia on trial basis.

AT&T claimed that the new HSPA 7.2 service will be made available to its customers by the end of 2010 and would consider Chicago, Dallas, Houston, Los Angeles, Charlotte, and Miami as its first six markets. However, the company wasn't specific about the time it would take for every 3G market to get the improvement, since AT&T's 3G sites can't take advantage of HSPA 7.2 until the optical fibre framework is completed.