How to hide (to my carrier) the use of VoIP? I plan to use Voice over IP with my android phone (Android 2.3 via Skype, Fring, JaJah, Line2 etc.). As I've read that my carrier is filtering VoIP protocols, I wondered if there are some protocol wrappers available as a workaround of packet/protocol filters? Thank you for any suggestions.
You could use a VPN to "mask" all your traffic. This way your provider would still be able to count the amount of data transfered -- but he would no longer be able to see its contents.

VPN requires a client (which comes already integrated with recent Android versions -- but additionally, there are a lot of apps available for this on the Google Playstore) and a server. The latter you can establish on your own hardware (software is available for most operating systems -- even some routers have this capability built-in). Alternatively, there are providers available offering VPN as a service.

The TechRepublic has a quite detailed article on this topic: Securely connect your Android smartphone via VPN. It describes what can be done this way, and also includes the necessary steps to set up everything. So if this approach sounds good to you, follow the link for more details.

Other good sources can surely be found following the vpn tag here on ASE.