Is sending text messages via mobile phone unnecessarily considered extravagance?

If messages incur expense, time, or effort without need, then this is extravagance (tabdhir), which Allah has forbidden. He described the extravagant as brothers of the devils, as stated in Surat Al-Isra: "And give the kinsman his due, and the needy and the traveler. And do not spend wastefully. Indeed, the wasteful are brothers of the devils, and ever has Satan been to his Lord ungrateful."