When Samsung unveiled the Galaxy S4 to the world, it promised that it would be a truly global phone by supporting more bands than any other LTE-enabled device currently on the market. It is a bold promise that Samsung may be able to back up in many places, but the United States is sadly not one of them.

To understand why this is the case, we have to revisit the sad state of mobile network systems in the United States. The US is split down the line between carriers that use CDMA2000 as the base network technology platform and those that use GSM/UMTS. This split was caused because there was no specific standard chosen by the FCC for digital systems when the PCS licenses were being auctioned. Instead, the FCC wanted to allow the market to decide that.

By itself, this platform split is not a problem anymore. These days, there are a lot of radio components used for CDMA2000 and UMTS devices that support both standards at the hardware level. The cost of supporting both standards in devices is low. However, American carriers have no incentive to support frequencies and standards that they don’t use. This is why devices for Verizon, Sprint, and AT&T only support their own networks. Typically, a phone from AT&T will not work on Verizon or Sprint and vice versa.

This is compounded by the problem that there are incentives to actively prevent cross-carrier compatibility on devices, particularly desirable ones like the iPhone. For example, the iPhone 5 for AT&T has the required duplexers, filters, power amplifiers, and antenna for T-Mobile’s band IV (AWS, 1.7/2.1 GHz) WCDMA network. However, it is disabled in the baseband software. All AT&T LTE devices have similar blocks. This is because the radio parts that enable AWS LTE also enable AWS WCDMA. The block on AWS WCDMA decreases the portability of AT&T devices significantly. But the carriers often argue that it isn’t feasible to offer broad compatibility (especially in regards to 700MHz), so let’s take a look at that.

Samsung touted that the phone can support six bands for LTE. This makes sense for the global LTE-enabled model, which will likely have LTE bands 1 (IMT, 2.1GHz), 3 (DCS, 1.8GHz), 5 (Cellular 850, 850MHz), 7 (IMT-E, 2.6GHz), 8 (Cellular 900, 900MHz), and 20 (EU Digital Dividend, 800MHz). But, six bands are actually enough to support the bulk of the LTE networks in the Americas as well. Hypothetically, Samsung could release a single American model that supports LTE on bands 25, 4, 26, 17, and 13. This hypothetical model could also support quad-band GSM, quad-band WCDMA with HSPA+42, and tri-band CDMA2000. Seems like a lot to stuff into a phone, right?

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