Vic Ahmed, president of the Colorado security firm SecCon- One, said his company recently went to an Internet telephony system when it moved into new digs.

He estimates the company saves about 20 percent to 30 percent a month on its bill compared with traditional land-line telephone services. Plus, there isn't the upfront cost of investing in a PBX, a traditional call-routing device.

"It's a no-brainer," for a business starting from scratch or relocating, said Ahmed, whose company has 15 employees.

Ahmed uses a system marketed by WavMax and IP5280 Communications, two Colorado firms that recently announced a partnership to provide wireless Internet telephony services to small- and medium-sized businesses across the Front Range.

Such Internet telephony, or voice over Internet protocol, offerings are proliferating as alternatives to traditional land-line telephone systems. Qwest, the dominant land-line company in the area, itself is increasingly selling VoIP systems.

Wireless VoIP is a twist on VoIP. In this case, the calls are transmitted over WavMax's wireless network, but the desktop setup with a plug-in phone resembles a traditional system.

The WavMax/IP5280 offering is typical of the sophisticated features seen in many VoIP offerings these days: the ability to send voice mails to e-mail inboxes, an auto attendant that routes calls and simultaneous ringing at multiple phones.

Said Jeffrey Pearl, IP5280 managing partner, "You can transfer calls from one (corporate) site to another as if you're in the same building, and it allows a small business to look large (with the auto attendant feature)."

Consumer watchdogs warn voice breakup can be an issue with some VoIP services, and high-speed Internet service is necessary. Ahmed said there were glitches at first but that he now can't tell the difference between his new system and a traditional land line.

John Taylor, WavMax chief executive, said the company has sold VoIP services for about 1 1/2 years but just started marketing the higher-end IP5280 product.

Evergreen-based WisperTel also has been offering wireless VoIP services for 2 1/2 years and has several hundred residential and business customers, said Barry Pier, chief executive officer.

"VoIP is more efficient, costs less," Pier said. "John Q. Public has got to get over the perception that it's a computer talking to another computer with a headset."