An upgrade for CDMA 1xRTT networks that provides up to four times greater capacity.
In most networks, newer devices use LTE for both voice and data whenever possible.
But older devices use CDMA 1xRTT (and 1x Advanced) for voice and text messaging, while for data they use CDMA 1xEV-DO and/or LTE networks. Therefore the benefits of 1x Advanced apply mostly to voice service.
The four times greater capacity means that a network upgrading from 1xRTT to 1x Advanced can handle four times as many voice calls using the same radio spectrum. Or - more likely - it can handle the same number of voice calls in one-fourth the radio spectrum, freeing up radio frequencies (bandwidth) for additional 1xEV-DO or LTE service, to handle growing demand for high-speed data service.
To achieve the full four-times capacity boost, all phones must support 1x Advanced as well. Carriers see some immediate benefit when upgrading network towers to 1x Advanced, but only realize the full four-fold capacity boost over time, as consumers upgrade to newer phones that support 1x Advanced.
A 1x Advanced network can optionally be configured by the carrier to provide greater coverage compared to 1xRTT, at the expense of the improved capacity benefit.