The rise of social messaging apps on smart phones has led to a decline in text messaging activity. It’s costing mobile providers an estimated $13.9 billion in potential revenues, a figure that’s jumped 60% in the last year, according to a new study. Short text messages are as high margin as they come for wireless carriers. But that $13.9 billion isn’t disappearing into thin air–it’s going straight into data plans. Calling is dead. Voicemails are beyond dead. Texting, you’re next. [Source: Bloomberg]