Hey all you iPhone users heading to SXSW this week: good luck Twittering, texting and making phone calls. The annual SXSW geekfest has been well underway and already reports for iPhone reception is dismal.  This is likely the first year thousands of iPhone users have descended on Austin and AT&T is unprepared.  A recent update says the company is adding capacity but it may be a good idea to buddy up with a friend on a different network just in case.