Apple has filed more than 300 patents related to the technology behind the iPhone.

LG Electronics claimed the iPhone's design was copied from the LG Prada. Woo-Young Kwak, head of LG Mobile Handset R&D Center, said at a press conference, “We consider that Apple copied Prada phone after the design was unveiled when it was presented in the iF Design Award and won the prize in September 2006.

On September 3, 1993, Infogear filed for the U.S. trademark "I PHONE" and on March 20, 1996 applied for the trademark "IPhone". "I Phone" was registered in March 1998, and "IPhone" was registered in 1999. Since then, the I PHONE mark had been abandoned. Infogear's trademarks cover "communications terminals comprising computer hardware and software providing integrated telephone, data communications and personal computer functions" (1993 filing), and "computer hardware and software for providing integrated telephone communication with computerized global information networks" (1996 filing). Infogear released a telephone with an integrated web browser under the name iPhone in 1998. In 2000, Infogear won an infringement claim against the owners of the iphones.com domain name. In June 2000, Cisco Systems acquired Infogear, including the iPhone trademark. On December 18, 2006 they released a range of re-branded Voice over IP (VoIP) sets under the name iPhone.

In October 2002, Apple applied for the "iPhone" trademark in the United Kingdom, Australia, Singapore, and the European Union. A Canadian application followed in October 2004 and a New Zealand application in September 2006. As of October 2006 only the Singapore and Australian applications had been granted. In September 2006, a company called Ocean Telecom Services applied for an "iPhone" trademark in the United States, United Kingdom and Hong Kong, following a filing in Trinidad and Tobago. As the Ocean Telecom trademark applications use exactly the same wording as Apple's New Zealand application, it is assumed that Ocean Telecom is applying on behalf of Apple. The Canadian application was opposed in August 2005 by a Canadian company called Comwave who themselves applied for the trademark three months later. Comwave have been selling VoIP devices called iPhone since 2004.

Shortly after Steve Jobs' January 9, 2007 announcement that Apple would be selling a product called iPhone in June 2007, Cisco issued a statement that it had been negotiating trademark licensing with Apple and expected Apple to agree to the final documents that had been submitted the night before. On January 10, 2007 Cisco announced it had filed a lawsuit against Apple over the infringement of the trademark iPhone, seeking an injunction in federal court to prohibit Apple from using the name. More recently, Cisco claimed that the trademark lawsuit was a "minor skirmish" that was not about money, but about interoperability.

On February 2, 2007, Apple and Cisco announced that they had agreed to temporarily suspend litigation while they hold settlement talks, and subsequently announced on February 20, 2007 that they had reached an agreement. Both companies will be allowed to use the "iPhone" name in exchange for "exploring interoperability" between their security, consumer, and business communications products.