Text Synchonicity

I had a voice message this AM from a friend who wanted to know in what room a certain class was being held in. I sent a text message back and spent a long time entering it, as my user interface sucks At the end of the message I said "don't bother to send a text back as I will only have to pay to read it." Four hours later a get a text message from a different friend (who does not know the first) from the other side of the country, who says "No reply at all....."