Not receiving MMS w/ ting on my Samsung SIII

Symptom:  People did not receive pictures we sent and we did not receive pictures that they sent.

Environment:
Pam using a Samsung Galaxy SIII, stock rom, rooted, but without the latest patch.
James using a Samsung Galaxy SIII, CM10 rom, using cm-10-20121118-NIGHTLY

Solution for Pam's phone:

• dial ##DATA#
• select Edit
• enter MSL (obtain from ting, or go to the website, find Account, Device Settings, Select the phone number, and the MSL is under it)
• select Others
• select MMSC URL
• change from http://mms.sprintpcs.com to http://mms.plspictures.com
• save and reboot

Solution for James's phone:

• It seems there was no obvious way to natively edit the MMS setting with CM10.  Various sources indicated I needed to edit a file.  To make things easier, I installed DropBear SSH server.
  https://play.google.com/store/apps/details?id=me.shkschneider.dropbearserver
• SSH in, then remount the file system:
• root@android:/ # cd /system/etc
• root@android:/system/etc # mount -o rw,remount /system
• Using vi, I altered /system/etc/apns-conf.xml to replace references for mms.sprintpcs.com to be mms.plspictures.com
• Rebooted, MMS now works.  Reboot may not have been necessary even.