Hi, just had this problem happen to a colleague of mine. She couldn't receive or send SMS or MMS messages. She could send and receive messages from other iPhones with iMessage.
This was not an android vs iPhone issue. She was not receiving confirmation texts from services.
We have a business account which gives you access to all of the account features per line. So I went into her line and removed SMS, MMS (picture messaging), and pay per text. Pay per text is free, but I guess it ties into the messaging features. Anyway. After disabling those and re adding them, texting started working.
There was no interaction on her part to get it working. No resetting network settings, rebooting, resetting to factory defaults, no swapping sim cards or anything else. Simply disabling/blocking text messages on her line and adding/unblocking them at the account level fixed it.
Hope this helps some of you! Not sure if this will solve intermittent or one way texting issues, but worth a try. In her case it was not working either way, sending or receiving and was for all messages. It randomly started happening and there is no telling what caused it.