iPhone maker Apple has technology to stop "objectionable" messages sent on its machines.
A patent, first submitted in 2008, is aimed at stamping out "sexting" on the iPhone. However, the patent will also enable Apple to view every iPhone user's texts.
According to the TechCrunch blog, the patent states in part that currently there is "no way to monitor and control text communications to make them user appropriate".
"For example, users such as children may send or receive messages (intentionally or not) with parentally objectionable language."
And of the patent itself: "In one embodiment, the control application includes a parental control application.
"The parental control application evaluates whether or not the communication contains approved text based on, for example, objective ratings criteria or a user's age or grade level, and, if unauthorised, prevents such text from being included in the text-based communication.
"If the control contains unauthorised text, the control application may alert the user, the administrator or other designated individuals of the presence of such text.
"The control application may require the user to replace the unauthorised text or may automatically delete the text or the entire communication."
Apple boss Steve Jobs this year attacked rival Google for allowing pornography on its Android phones, saying: "You know, there's a porn store for Android.
"You can download porn, your kids can download porn.
"That's a place we don't want to go - so we're not going to go there."
However, the push for further smartphone monitoring has worried privacy groups and many users as phone makers such as Apple collect a variety of data, from geolocation data through to call times and credit card details, to pitch ads and other information at phone users.