Is it possible that some iPhone text messages may not send to the receiver?

Well I asked one of my friends if she received one of my text once, since she never responded, and she said no.
So my question is, is it true that some iPhone text messages may not properly be sent to the receiver?
Also, how can you tell if someone received the text or not on the iphone 4?

That's possible for any phone on any network. They aren't perfect. Usually if a message fails to send you would be notified.

If I remember correctly there are options for delivery reports on the iPhone 4. Try that.

Delivery of text messages is never guaranteed, with or without an iPhone.

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