Smartphone messaging apps like iMessage and WhatsApp are growing more popular than the regular SMS texting, according to a new study. Last year 19.1 billion messages were sent and received each day over Blackberry Messenger, iMessage, WhatsApp, and Nimbuzz. Meanwhile around 17.6 billion SMS messsages were sent out each day last year. The also says the number of chat app messages sent each day will rise to about 41 billion per day this year.