A small internet phone provider has been forced to scrap its ad campaign parodying the end of a relationship, targeting rival company Telus.

Shift Networks, which offers Voice over Internet Protocol or VoIP to businesses, recently launched an advertising campaign in Calgary, Edmonton and Vancouver.

Billboards in the promotion contained advertisements written in the form of a breakup letter to Telus.

Telus sent a letter to Shift, claiming the ads violated its trademark rights.

"I think it speaks to some issues we have in the Canadian telecommunications marketplace that a company with 90 per cent plus market share of wire line services doesn't want us referencing their name to make awareness that there is a legitimate alternative," said Trent Johnsen, president of Shift Networks.

VoIP allows consumers to make telephone calls using a broadband internet connection instead of a standard analog phone line.

Telus spokesman Jim Johannsson said when companies launch comparative advertisements, they typically explain why their product is superior with information such as pricing.

"In this case … this competitor chose to disparage the Telus brand instead," Johannsson said. "So really they're doing a disservice to consumers while at the same time trying to damage the Telus brand."

Shift agreed to remove some of its billboards and cover up references to Telus in others.

In May 2005, the Canadian Radio-television and Telecommunications Commission ruled that it would regulate internet-based phone service with the same standards as any other local phone service, meaning large telephone companies such as Bell and Telus cannot offer internet-based phone services below cost.