If you want to use a type of VPN that isn’t supported by the built-in Android client, such as SSL, you’ll need to find third-party client software to install on your phone. Different vendors of SSL VPN appliances implement their VPNs in different ways, so you should contact the vendor to find out if they make client software for your phone’s platform. Cisco recently announced the release of theAnyConnect SSL VPN client for Android, which is available from the Android Market at no cost. It’s currently only supported for Samsung devices (Galaxy S/S II and Galaxy Tabs) but will also work on other Android devices if they’re rooted.
The implementation of SSL VPN used by Windows Server 2008 is called SSTP (Secure Socket Tunneling Protocol). It’s fast and stable, but unfortunately, it only support Windows 7 clients.
Using a VPN to connect your smartphone to your home or work network can expand the usability of your phone and help you to be productive no matter where you are. The VPN client that’s built into the latest versions of Android work fine for creating basic PPTP and L2TP based VPNs, and there are third-party clients available — many of them free — if you want more options and/or want to connect to an SSL-based VPN.
If you use a different phone platform, note that the iPhone, Blackberry, Windows Mobile, and Symbian also support virtual private networking. The Nokia built-in VPN client requires Nokia’s VPN policy servers. At this time, Windows Phone 7 does not include support for the common VPN protocols (PPTP, L2TP/IPsec). It only supports SSL VPN (SSTP) through a Unified Access Gateway (UAG) using Exchange (on site or hosted).