By Robert Schoon (r.schoon@latinospost.com) | First Posted: Dec 07, 2013 03:53 PM EST

T-Mobile has begun upgrading its LTE service for faster speeds by using some of the spectrum it acquired in its MetroPCS purchase. The rollout just began in late Nov., but T-Mobile plans to offer the LTE expansion in its top markets soon.

T-Mobile is managing to provide better coverage and faster speeds by combining T-Mobile's LTE airwaves with part of the spectrum held by MetroPCS, which the uncarrier's parent company Deutsche Telekom acquired for $1.5 billion earlier this year. Combining the two, according to AllThingsD, allows "20-by-20 service" which is double the range of radio signals originally offered by T-Mobile in most of its markets.

What does that mean for T-Mobile customers? Increased bandwidth without lifting a finger. Since this is an upgrade on T-Mobile's side, customers won't need to change or upgrade their LTE-capable devices to benefit - that is, once T-Mobile upgrades its service in their area.

Right now, the only customers benefiting from the combined spectrum LTE reside in parts of North Dallas, which is the first and only place T-Mobile has flipped the switch. However, according to the AllThingsD report, T-Mobile plans to offer the MetroPCS-expanded spectrum in 90 percent of the top 25 U.S. markets, meaning the biggest cities will see improvements first. "We actually have been working on it for a while," said T-Mobile network vice president Grant Castle to AllThingsD.

With the prices of smartphones in steady decline, more and more people in the U.S. are likely to own a data-hungry device. A Pew survey from earlier this year found that, for the first time, a majority of Americans owned a smartphone. In response, all four major carriers in the U.S. are working to expand their coverage, capacity and speed. T-Mobile, for one, is still working to expand its LTE coverage, and expects to have so-called 10-by-10 LTE in 40 of the top 50 markets by the end of the year, according to the report.

In the largest cities, where every carrier already has 4G LTE service, magnifying an already competitive race, the only means to get an edge is upgrading LTE for the fastest speeds possible.

All four carriers are working on this. For example, Sprint recently announced "Sprint Spark," an ultra-fast wireless data plan with speeds up to 60 mbps, which Big Yellow has deployed in New York City, Los Angeles, Chicago, Tampa and Miami, with about 100 cities slated to get the service in the next years. But unlike the T-Mobile upgrade, customers need to buy tri-band devices to use all of Sprint's wireless spectrum bands at once to achieve "Spark" speeds. Sprint only has four for sale so far.

Verizon is working from a different angle, adding AWS spectrum to its LTE network, which requires only a software update to work. That move is aimed at enhancing capacity in high-traffic areas in cities, making the service more reliable, if not raising the speed limit to ludicrous. Meanwhile, AT&T is working on a $14 billion overhaul and upgrade called Project Velocity IP.