Many of mobile phone fabrication and also the Operator, in this time, launch a smart phone / mobile phone that also by default run an Instant Messenger in it. It including Personal Phone Instant Messenger just like Ping in iPhone or BlackBerry Messenger in BlackBerry Smart Phone.
Others Smartphone developers also launch this kind of Instant Messenger Phone to Phone, such as Nexian Messenger. Using Instant Messenger / Chatting with PIN (like username / Chat ID) in Mobile Devices (BBM for example) would make us deliver messages faster and cheaper.
In the other hand, Short Message Service that also known well as SMS is another kind to deliver messages.
The purpose of both of them (Instant Messenger and SMS) is the same. It for communication in text messages.
All of the Operator (almost) applied charge on SMS per text message but not for Instant Messenger (it only apply for internet connection that Mobile Devices used). This could means that SMS is more expensive than using Instant Messenger. SMS also by default has been limited only 160 character. Instant Messenger has more character than the traditional text message like SMS.
By combining Instant Messenger by default in Mobile Devices this could means a thread to SMS text Message? Who knows. Might be in the future SMS would be replaced by anInstant Messenger (As we might already knew accross BBM users, it been really familiar that we used BBM as a text messages along BBM to BBM than used ordinary SMS text messages).