I would suggest doing a hard reset or restore on your phone. This will erase all your data on your phone. Make sure you have contacts backed up with backup assistant. I would sure hope that would clear the problem.
I'm sorry to learn your Samsung Trance is having issues with being stuck in headset mode, as well as it placing calls automatically to people when you open your texts. Let's see what we can do. How long have you had your phone? When did this start happening? Has it been dropped or exposed to liquid at all? You can try removing battery for 30 seconds and restart to see if it fixes issues. Otherwise, as archeryhunter1993 mentioned, you can try a Master Reset.
* From the main screen, press OK to choose Menu.
* Select Settings & Tools then press OK.
* Select Phone Settings then press OK.
* Select Security then press OK.
* Enter the Phone Lock Code (default is the last 4 digits of the phone number) then press OK.
* Select Restore Phone then press OK.
* Select Yes then press OK.
* Press OK.
* Enter the handset lock code (default is the last 4 digits of the phone number) then press OK.
I trust this information is helpful.
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