CHICAGO—CDMA has more than a decade's worth of life left in it, a panel at the 4G World trade show said today, increasing the chances that any rumored Verizon iPhone will run on the carrier's legacy 3G CDMA network.

"It's going to be here for a long time, and it's going to coexist with LTE," said Adolfo Masini, a vice president at Alcatel Lucent. "It takes time for new technology to roll out, and CDMA is absolutely essential for the success of LTE as well."

As Verizon celebrates its upcoming LTE network and evidence comes together about an upcoming Verizon iPhone, one of the hot questions is whether the iPhone will run on the carrier's new, 4G LTE network or its older, 3G CDMA network. At the panel today, panelists emphasized that any device on a network like Verizon's that needs comprehensive voice coverage will probably have to stick with CDMA for quite a while.

The panel spent some time beating down myths about CDMA, such as that it's an infrequently used technology. While CDMA doesn't have quite the scale of GSM, it's used by 340 carriers in 120 countries and has a major user base in China, the panel said.

"There are 550 million people in the world using CDMA 1X or EVDO," said Joe Lawrence, vice president for marketing at the CDMA Development Group. "CDMA is going nowhere. It's driving competition, and it's creating enormous economies of scale."

Verizon's CDMA technology has been criticized for not allowing simultaneous voice and data connections and for having maximum speeds that are slower than the HSPA+ offered by AT&T and T-Mobile. Earlier this month, Verizon announced plans to roll out 4G LTE to 38 U.S. cities. LTE, which all the major U.S. carriers except Sprint have plans to adopt, will offer data speeds up to four times as fast as Verizon's current CDMA EVDO Rev A network.

Verizon rejected the next form of CDMA, known as Rev B. But even for carriers who aren't going to Rev B, CDMA isn't a dead-end technology, the panel members said. Two major new advancements, 1X Advanced and DO Advanced, will help CDMA networks keep their 3G systems fresh even as they lay down 4G networks as well. Verizon has also said they're working on an upgrade called Voice Over Rev A (VORA), which will enable simultaneous voice and data connections on CDMA.

"If you can consolidate your voice traffic into a third or a quarter of the number of carriers, that frees up spectum," said Paul Challoner, a vice president at Ericsson. "I can use this improvement … in terms of capacity, or can trade that off for a 65% coverage improvement."

DO Advanced, meanwhile, can improve data speeds and capacity through various software upgrades even on existing EVDO Rev A networks, Motorola product management director Kim Flowers said.

The panelists agreed that it's going to be a while before voice-over-LTE solutions become as cheap and as efficient as CDMA. That means carriers like Verizon and MetroPCS may be relying on CDMA for years.

"I believe that voice-over-LTE will take a long time," said Sean Cai, chief technical officer of handset and infrastructure manufacturer ZTE. "Circuit-switched [voice] is going to be a fallback."