Bad times or not: Be careful if you're considering switching to a new-fangled phone service to save money. Few companies raise the ire of small-business owners more than Verizon ( VZ), AT&T ( T), Cablevision ( CVC), Time Warner Cable ( TWC) and Qwest ( Q). So it's no surprise that a tide of low-cost telecom companies is trying to cash in on the angst. Vonage ( VG), Fonality, Nextiva and others offer conference calling, call forwarding and unlimited usage at dirt-cheap prices. In these lean times, it's a tempting way to save. Turning on Toktumi: Last fall, I tested Toktumi, a low-cost telecom service targeting small businesses in my little digital world. Founder Peter Sisson, 46, had what seemed like a breakthrough idea: create a virtual phone system without the phones. For $15 a month, San Francisco-based Toktumi gives users a dedicated number that hosts incoming and outgoing calls made on home or mobile phones, or the Internet. The Web-based system works with any existing landline, cell phone or computer. The service includes unlimited calling, a sophisticated online assistant and other cool business tools. At first, it worked as advertised. The service created a professional-sounding number for my business, Blumsday. It connected with the beehive of test phones and communication devices I use. The system also ran flawlessly on a variety of computers. Voice quality depended on the Web connection; sometimes things worked and sometimes they didn't. Toktumi's a valuable tool, particularly for individual users looking for a business number on the cheap. But for larger companies, even those with just a few extensions, Toktumi presents serious challenges, based on my tests.