Yell has threatened to sue a father and daughter from Sussex who set up a business listings website.
Yellowikis was launched in 2004 by Paul Youlten and his 14 year-old daughter Rosa Blaus, and now has 5,000 listings for firms around the world. According to wiki conventions, any site visitor can create or edit a listing.
Yell, the Yellow Pages website, has argued that users could confuse Yellowikis with its own site and is threatening legal action over intellectual property rights.
Yell also wants Youlten to hand over Yellowikis' four different web addresses.
Solicitors for Yell stated that that they will seek damages and an injunction if their requests are ignored.
"Yell takes its brand and intellectual property seriously. Like any prudent brand owner it seeks to protect it," a Yell spokesman told BBC News.
Youlten has insisted that Yellowikis is not deliberately pretending to be Yell. "We have a different sort of perspective than Yell. We consider ourselves to be a global business listing," he said, adding that the site is run as a " not-for-profit hobby".
A solicitor for Youlten is currently looking at Yell's request. Meanwhile, site visitors are being asked to suggest a new name and contribute to the legal defence fund.
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