Infrastructure - The US consists of a fragmented set of wireless technologies and standards, with both GSM and CDMA based carriers. The iPhone 3G utilizes GSM-based standards, making the partnership with AT&T the most lucrative in terms of access to subscribers. However, moving forward to 4G and beyond, if there is a convergence of standards and interoperability, a much larger market in terms of potential subscribers could present itself for the iPhone. While wireless infrastructure issues may not have dramatically impacted the success of the iPhone historically, changes in wireless infrastructure could have a dramatic impact on future success, and Apple would be well advised to monitor developments in 4G technologies and beyond. Another factor to be considered is the widespread fixed-line Internet access infrastructure in the US which may have led to the slow adoption of mobile Internet services. As discussed previously, iPhone is adept at replicating the fixed -line Internet experience, which gives the iPhone a clear advantage in the US (until competitors potentially catch-up to its technologies and functionality with respect to mobile web browsing.) To do so, Apple has capitalized on the Wi-Fi infrastructure in the US, as the iPhone is capable of utilizing Wi-Fi connection to access the fixed-line Internet giving users get the same level of services with reduced cost and increased responsiveness.