"Obviously, it gives us flexibility," Houck said. Nortel's service and support has been excellent, making the switch a natural choice, he added. "They've been a good company, and maybe we could buy them cheaper, but we've stuck with Nortel because of good service."

Siemens said it has several customers already deploying its new MobileConnect products, but none were available for interviews. One is a major clothing retailer and manufacturer in Europe with 1,000 stores and 32,000 employees, Roy said. It is able to use the dual-mode network with an existing HiPath 8000 PBX and Nokia E60 and Fujitsu-Siemens Pocket LOOX dual-mode handsets, Roy said.

The benefit of dual-mode capability is that users have a single number and one mailbox for e-mail as well as seamless roaming across Wi-Fi and GSM cellular networks, Roy said. The Siemens technology is based on Session Initiation Protocol and, as such, is the first dual-mode capability of its kind, he said.

Chris Silva, an analyst at Forrester Research Inc. in Cambridge, Mass., said the Siemens MobileConnect product will do well in industries like health care and manufacturing. "When you look at the advantage to health care, the benefit of reaching a surgeon across cellular and Wi-Fi networks is pretty clear, but the benefit to a salesperson is a little fuzzy," Silva said.