For a long period of time I've been using SlimBean with my old Galaxy S, where it wasn't needed to activate data connection by myself to send or receive MMS. That process was done automatically.
Yesterday I bought S3 and I found out that Samsung and/or Google do not implement this feature in their latest firmwares, which is strange.
I've done a small research in Google and found a post by the member Ouzo here in our forum, who has a resolution for this problem.
Here it is:
For me, the fix was to add this line to my 'others.xml' which is located in the System/CSC folder.
You need to add the above string before the end of the xml file - the last two lines of it should be:-
Some people don't have an 'others.xml', they have 'Features.xml' or 'Features_Default.xml' instead.
After editing the xml file, you need to change the permissions back to rw--r--r--
After setting the permissions, reboot.
To make these changes I use ES File Explorer and its built in text editor (it's free).
Needless to say I hope, your phone must be rooted to edit the above file. Make a backup of the file before editing it.
I hope that many of you will find this information useful.