Copper cables, optical fiber and leased lines aren't as sexy as the music phones and mobile video services that are in the limelight at the CTIA Wireless show in Orlando this week, but they're on a lot of people's minds.

Wireless networks have to come back to Earth eventually in order to talk to the Internet and the traditional wired phone network. What gets them there is backhaul, which typically has meant a T-1 leased line (1.5M bits per second) to each cell site. As the speed of cellular networks approaches the point where that's only enough bandwidth for one subscriber, mobile operators have turned to using three or more T-1s.

Vendors and some observers say that can't last: Operators will need new technologies to feed cell sites that will be expected to support 3G (third-generation) services such as HSDPA (High-speed Downlink Packet Access) and EV-DO (Evolution-Data Optimized) Revision A under heavy use. Future 4G services will demand even fatter pipes -- hundreds of megabits per second, estimates Michael Howard of Infonetics Research Inc.

That doesn't mean 3G users will see their phones grind to a halt, said IDC analyst Godfrey Chua. Data services use is growing quickly, but not explosively, which gives carriers a breather. That said, the alternatives to leased lines present challenges, according to Chua. WiMax high-speed wireless and even metropolitan Ethernet don't necessarily deliver the same reliable quality yet, Chua said.

If operators just add T-1s, eventually they'll be squeezed, Howard said.

"There's all this bandwidth being added, but what a carrier can charge per month is staying fairly flat because of competition," Howard said. What's needed is not just more capacity but a more economical form of connectivity to the cell site, he said. Ethernet -- over fiber, copper wire, or even point-to-point wireless -- will make up most of this, according to Howard. For various reasons, microwave is turning into the choice for Europe, said IDC's Chua said.

Telecommunications vendors are eager to aid in the transition. Executives of Nokia Siemens Networks, the infrastructure company that is set to debut next week, told press and analysts at CTIA that they see a "paradigm shift" in cellular backhaul. Nokia Siemens sees huge potential for its optical and microwave infrastructure gear, and possibly for wireless mesh technologies, which can cover a large area with just a few links to the wired network.

The IDG News Service is a Network World affiliate.