Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
I vote you're fine, it shouldn't affect carrier useage... but I don't have a phone to upgrade to ios 6 so I can't test. You may want to ask this in the ioc 6 forum :)
 
Internet and text work just fine. I never did set up MMS so I don't know if it affected the jail break. Panorama is cool!
 
Tmobile sim trick still works... sort of.

ok so I upgraded to ios6 this afternoon but kinda forgot that my jb would of course be lost and I had tetherme mostly to expose the APN settings. BEFORE I had the jb tho I had used what many had discovered-- that when you insert a T-mobile sim the APN settings become available. NOW what I see is that apple has patched that somewhat-- if you leave the Tmo sim in the phone will quickly reset and lock you out-- what worked for me was to insert the Tmo sim and then navigate to Settings>General>Cellular>Cellular Data THEN quickly replace the Tmo sim with the Straight Talk sim-- for me, the APN settings were still exposed and I could enter the following--

Data APN att.mvno
Data APN Username
Data APN Password
MMS MMSC http://mmsc.cingular.com
MMS Proxy 66.209.11.33:80

(leave everything else blank)
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.