APN and MMS Settings for Straight Talk

While Straight Talk's documentation card does provide APN settings, there's a couple extra ones required to get an iPhone correctly supporting MMS and iMessage.  In particular, the MMS UA Prof URL should be set to this: 

http://www.apple.com/mms/uaprof.rdf

Without this setting, MultiMedia SMS (MMS) may not be supported, even when iMessage is disabled.