What would you say if someone said he was frum but has to go to McDonalds once a week and have a cheeseburger. You wouldn’t think of him as frum and I bet you wouldn’t eat in his house. This is the same thing. Texting is being mechalel shabbos just like people who drive. They should institute here like they have in Israel the KosherPhone and rabbanim here should insist that everyone who must have a cell phone get one of those then there would be no texting or internet on phones at all. That would solve the problem.
Also why do yeshivos and seminaries in E”Y not only allow but insist that the kids have phones. I hear how you could say its for safety but if this is the true motive you can have them rent pagers instead.