(AP) -- Sprint Nextel Corp. and Verizon Wireless are building wireless data networks using new technologies that the industry calls fourth-generation, or 4G. Not to be outdone, T-Mobile USA launched a campaign this week that calls its own upgraded network "4G."
T-Mobile's network is based on what the rest of the industry considers 3G technology. But T-Mobile says calling it 4G is justified because downloads are as fast as the new 4G networks.
"When consumers look at 4G ... if you ask nine of ten, they'll say it's about the speed," T-Mobile spokesman Reid Walker said.
Previously, T-Mobile has referred to the network as "offering 4G speeds," but it's giving up that qualification to call it "America's Largest 4G Network" in TV ads that started Tuesday evening.
T-Mobile is a unit of Deutsche Telekom AG of Germany. Its German wireless arm has performed similar upgrades, but it isn't calling its network "4G." In Sweden, the technology used by T-Mobile is known as "Turbo 3G."
Sprint Nextel spokeswoman Stephanie Vinge said the 4G tag isn't just about speeds, but rather it's about the underlying technology. She said T-Mobile's network doesn't qualify.
Sprint's Clearwire Corp. subsidiary is building a network using WiMax technology, which qualifies as 4G under the common industry definition. Sprint started marketing its first 4G phone this summer, but it still uses Sprint's 3G network for calls and text messages.
Verizon Wireless is using another technology known as "Long Term Evolution," or LTE, to create a new data network. It's scheduled to light it up in 38 markets before the end of the year.
For downloading large files, LTE and WiMax in their current incarnation aren't faster than the "HSPA+" technology used by T-Mobile. But they use radically different method to transmit information, and they're designed from the ground up for data traffic rather than calls. Those two factors qualify them as 4G under the common industry conception of the term.
Sprint didn't say whether if it would challenge T-Mobile's advertising in court or with the advertising industry's self-regulatory panel. Verizon Wireless had no comment on T-Mobile's campaign.
Last fall, Verizon Wireless and AT&T Inc. took each other to court over dueling claims about their networks in TV advertising.
Sprint and Verizon Wireless would face a problem if they want to shut down T-Mobile's campaign. The International Telecommunications Union, a standards-setting body of the United Nations, doesn't consider their LTE or WiMax networks to be 4G either. The ITU has ruled that only future versions of the two technologies, with vastly higher speeds, would qualify.
Explore further: Agencies differ on allowing in-flight phone calls (Update)