I find it interesting that if someones sends an SMS and it is rejected, the sender is not necessarily notified.<p>Most of the time I have SMS disabled on my phone (except for Google Voice). If someone on T-mobile (my carrier) sends me an SMS, they will get an error message, but people on other networks have no way of knowing that the SMS failed. Fortunately, most of my friends know that I prefer IM and the incorrigible texters have my GV number, but on occasion someone will try to SMS my actual phone number.