Existing Samsung Galaxy S III phones won't work with T-Mobile's LTE network

Existing owners of Samsung’s Galaxy S III will not be able to use the phone on T-Mobile’s LTE network, which debuted Tuesday and will reach 200 million people by the end of this year.

The Galaxy S III does not have a compatible LTE radio, said Randy Meyerson, senior director of product marketing at T-Mobile, during an event in New York City, where the company announced the official rollout of its LTE network and new mobile plans.

At the event, T-Mobile announced an iPhone 5 from Apple that will work on its LTE network. Other phones that will work on its LTE network include BlackBerry Z10, HTC One, and S3’s successor, Samsung Galaxy S4, which will go on sale starting on May 1. Samsung’s Galaxy Note II, which started shipping in September last year, will also work on T-Mobile’s LTE network, said a representative for the wireless carrier at the event.T-Mobile officials declined to comment on whether an LTE version of the Galaxy S III would become available.

The S III was announced last year and started shipping in the U.S. for all major networks starting in June. When announced, the smartphone worked on LTE networks from AT&T and Verizon, but T-Mobile at the time did not offer LTE and was working on deploying the network. The S III smartphone shipped with Qualcomm’s Snapdragon MSM8960 chipset, which includes an integrated LTE radio.

However, it remained unclear if the S III would work on T-Mobile’s LTE network. That led to discussion threads in T-Mobile’s forums and on other websites like XDA-developers on whether S III had forward support for LTE based on the MSM8960 chipset specifications. Forum members sent related questions to Samsung and T-Mobile representatives, but got mixed answers.

All S III phones use Qualcomm’s MSM8960 chipset, but Samsung and T-Mobile may have disabled the LTE capability on the smartphones designed for T-Mobile networks, said Anand Shimpi, a chip expert and founder of Anandtech, which reviews hardware.

Smartphones are planned starting roughly 18 months ahead of their release, and are designed for specific bands and frequencies, Shimpi said. It was likely too early for T-Mobile to determine what frequencies its LTE network would run on.

“You need the right front-end to enable LTE on the right frequency,” Shimpi said.

Qualcomm is trying to solve some of the LTE compatibility issues by cramming in support for a wide range of LTE bands in its chips, which could help smartphones interoperate on multiple networks in different countries, Shimpi said.