[Ken Clements]

Bought an AT&T Active S5 (Samsung) .. frequencies are all the same on Vodafone network, so figured it would work effortlessly, which it did with the default APN settings, except for MMS... kept getting "Multimedia Message not supported by Network". After some time on support to Vodafone (escalated to technical), no resolution.

Solution is using a different SMS/MMS messaging app as default, such as Google Messaging or HANDcent SMS... It would appear that the AT&T Samsung App is hardcoded to work with particular servers (I am guessing they are rerouting PXT to Homeland security for scanning). Change your SMS/MMS to a different APP instead of the Samsung default APP, it should work (with the default APN settings). It did for me with Vodafone.

[B. Diddy]

Good tip, thanks!