When you're not getting messages from Android users on your iPhone, try toggling Airplane mode, checking your block list, ...
You can enable MMS on your iPhone to send multimedia messages without using iMessage. Here's how to make sure it's enabled.
Apple and AT&T made MMS available to most iPhone users late Friday and it works just fine. All iPhone 3G or 3GS owners need to do is install one, piddly little update to their carrier profile on the ...