It worked for me, so I thought Id share with you. I cant speak for custom ROMS as Im on stock rooted.
edit: the symptoms I was having was I would send an MMS, and it would sit at sending. If I received an MMS, I got the notification of a new text with a download button. Hit that, and it sits at download. FYI I just checked my wifes SGS2 and she's on Darkside 2.7 and had the same issue. I perfomed the fix above, and now it works. So it appears this fixes the problem on GB as well.