HTC print ad brags about 4G devices on all Big 4 networks, including AT&T?

HTC has advertised before about being the first 4G smartphone manufacturer, with the HTC EVO, but an astute reader of Rolling Stone ad noted an ad where HTC brags about having the first 4G phone on each of the Big 4 U.S. wireless carriers. That ad would therefore have to include two unannounced phones on Verizon and AT&T, and it does. The question arises: what AT&T 4G?

It appears the HTC Thunderbolt name on Verizon is official, if it's appearing in a print ad, We know something about the Thunderbolt, but nothing really about the AT&T Inspire 4G except that HTC filed to trademark the name Inspire late last year.

The other two phones, the T-Mobile G2 and the aforementioned Sprint EVO have been out for some time, but this probably means we'll hear about the Thunderbolt and Inspire 4G at CES later this week, if this ad got the green light from both Verizon and AT&T.

Now, as to the question about 4G: Verizon just launched its 4G LTE network, but AT&T's network, although scheduled for a limited roll-out later this year, probably around mid-2011. How can HTC mention 4G on AT&T when the network isn't near being ready?

One possible answer is that AT&T is about to jump on the HSPA+ is 4G bandwagon that T-Mobile is using. T-Mobile claims it's HSPA+ network is 4G, while most consider it 3.5G at best. Meanwhile, AT&T hasn't peeped about the fact that it also has HSPA+ on its network. This could be a sign that AT&T has decided it better start saying it has 4G to compete with the other networks.

We expect more info as CES unfolds, starting on January 6.  Android Central has the full ad image at the link above.