I have checked out a few threads at xda-developers.com about getting SIP to work on the Galaxy S2 and the general
consensus is to use CSipSimple.apk. The current method posted at How To Add Native SIP seems to have some mic problems. Some users have suggested using CSIPSimple. Therefore, I have included it below for users to test.
Attached is CSipSimple, an apk for SIP on the Galaxy S2.
Problems? Check this out: CSipSimple Wiki
CSipSimple: CSipSimple-0.02-03.zip 2.76MB 28 downloads