An analyst has stated that the cause of the unusually high number of dropped calls some Apple iPhone users are experiencing may be down to the phone's Infineon chipset.

Apple user forums have been full of complaints about the dropped calls but Apple itself has stayed quiet on the topic.

However, Nomura analyst Richard Windsor wrote in a research note that the problem is likely to be down to the 3G chipset from German manufacturer Infineon.

"We believe that these issues are typical of an immature chipset and radio protocol stack where we are almost certain that Infineon is the 3G supplier," Windsor wrote in the report dated 12 August.

"There are too many instances on iPhone blogs and Apple's own website for it to be coincidence. Furthermore, it is not just the US but other countries as well."

Windsor claimed that the chipset software had not been widely tested enough in areas where cellular signals are patchy, and that the problems are similar to those suffered by 3G phones in Europe when they were launched five years ago.

However, Apple is now reportedly working on a software update to fix the problem, which is expected to be finished and sent out in the next few weeks.

"It is not about whether you have problems or do not have them," Ken Dulaney, a mobile analyst at research firm Gartner told The Wall Street Journal.

"It is how quickly you address them that matters. If Apple addresses them, people will cut them slack."