Cisco is suing Apple to prevent it from using the name iPhone after negotiations between the companies broke down.

It was revealed that Apple and Cisco were still discussing terms, even as Apple CEO Steve Jobs was demonstrating the iPhone for the first time.

However, Apple didn't get an agreement from Cisco, who has now filed a lawsuit in Federal District Court for Northern California seeking an injunction against Apple using the name.

Apple and Cisco have been in negotiations for about two years over Apple's desire to license the iPhone trademark, said Cisco spokesman John Noh. "Because they have been negotiating with us on licensing the trademark all this time, Apple is acknowledging that we own the name," said Noh.

"Cisco entered into negotiations with Apple in good faith after Apple repeatedly asked permission to use Cisco's iPhone name," said Mark Chandler, senior vice president and general counsel for Cisco.

"Today's iPhone is not tomorrow's iPhone. The potential for convergence of the home phone, cell phone, work phone and PC is limitless, which is why it is so important for us to protect our brand," Chandler said.

An Apple executive told our sister magazine, PC World magazine that because the Cisco iPhone is a VoIP phone and the Apple iPhone is a cell phone, Apple is not in violation of Cisco's trademark. "They're different products," said Greg Joswiak, Apple's vice president of worldwide iPod marketing.

But if Apple was in talks with Cisco to license the iPhone trademark, it would be "a dangerous move" for Apple to start using the iPhone name anyway, said trademark attorney Allonn Levy of law firm Hopkins & Carley in San Jose, California. "It could be seen as intentional infringement."

Levy says it's possible that Apple could argue that Cisco had not introduced any iPhone products until last summer and that Apple would consider the name available. But he also said Cisco may have filed the lawsuit in order to pressure Apple into signing the trademark licensing agreement the two companies had been negotiating.