Palm, Google and Microsoft have all stepped up their efforts to strengthen their smartphone line-ups as they increasingly try to challenge the popularity of the dominant Apple iPhone reports Reuters.

In several announcements on Tuesday, said companies have introduced wireless carrier partnerships, and new mobile phones and efforts ahead of the holiday season to boost the availability of new apps for their handsets.

Google has announced it is teaming with Verizon Wireless with a view to co-develop multiple handsets carrying the Android platform. Microsoft unveiled Windows Mobile 6.5 and expects more than 30 handsets with WinMo 6.5 in over 20 countries by the end of the year, and Palm has made their software more open to encourage applications.