5:30 PM -- It appears that Long-Term Evolution (LTE) saw a steady take-up late last year from early adopters of the new Verizon Wireless 4G service.

The operator reported that in the first three weeks after Verizon introduced LTE, it sold 65,000 dongles, 41 percent of which went to new customers. Verizon is expecting to have new smart phones within the first half of the year.

This doesn't mean, however, that all is smooth sailing for the 4G technology. Problems as diverse as interference and questions about net neutrality are likely set to dog LTE this year.

Chief amongst these concerns is the possibility that LTE might cause interference to cable-TV services.

Now, LTE upstart LightSquared has got entangled in a similar issue, with concerns that its hybrid LTE/satellite network could cause interference with technology like GPS receivers. Sanjay Ahuja, CEO of LightSquared, has sent a letter to the Federal Communications Commission (FCC) to say the company will ensure that its service plays nice with commercial satellites before going commercial.

The interference issue is one to watch worldwide. Simply because the chance of interference with existing services is one of the things that could actually hold up planned deployments of LTE.

The ability to roam between LTE networks is still very much up in the air too. Even in the US, the two existing LTE providers - Verizon and MetroPCS Inc. (NYSE: PCS) -- operate on two different bands and users couldn't roam between different cities, even if they wanted to.

This situation is likely to get worse, not better, at least in the short to medium term. A world phone for LTE would likely need to support 15 or more bands for 4G globe-trotting, making it unlikely until software-defined radio and battery-life technology are further improved.

In the U.S., meanwhile, there are still concerns about mobile net neutrality and how much access to apps is allowed over this new video-hungry network.

So, keep an eye on these issues. My sense is that most are unlikely to trip up much of the momentum behind LTE, but you never know. In particular, the possibility of interference to cable TV and satellites could potentially put the brakes on for some regulators and operators.

— Dan Jones, Site Editor, Light Reading Mobile